REVIEW - NUFORCE PRIMO 8 - AN AUDIOPHILE PHASE COHERENT QUAD BALANCED ARMATURE DRIVER IEM
 
BACKGROUND:
 
My first venture into the world of IEM was with the Shure E2c in 2007, when I wanted some isolation for private listening at home in bed. Prior to wanting the extra isolation I used some Bose noise-canceling headphones, because they helped remove the noise of my window air-conditioning unit. But I was mostly into using speakers, and felt that the entry level E2c didn't have the clarity or frequency balance of my vintage Polk Compact Reference SDA speakers. Those speakers are still amazing sounding today, despite the treble fading a few dB as the crossovers age and show signs of needing to be refurbished.
 
Within 6 months of getting the E2c I began to wish for an affordable upgrade that would give me more of an "audiophile" level of performance. I tried the jump to the Shure E4c and the detail and sonic balance was much improved, at the expense of having a less energetic and efficient performance, and worse bass impact. My iPod just didn't drive them very well. I then bought some $200 Denon IEM with dynamic drivers that had much improved efficiency and bass impact, at the expense of worse sonic balance and less accurate timbre and tone. At low volumes the sound was fairly enjoyable, with a "V-shaped" frequency response, but the sound would become fatiguing at higher volumes. That brought me to head-fi where I started looking for portable headphone amplifiers to improve the impact of my E4c without losing the sound quality.
 
After my introduction to Head-Fi it seemed like I began an almost endless journey through every popular IEM and portable amplifier, trying to see just how good audio reproduction in such a tiny package could get. During that time several IEM stood out well above the crowd for me, starting with the Westone 3 in 2008 when used with the proper tips for my particular ears. With silicone tips the treble could get a little boosted, and with triple flange tips the treble could sound a little artificial, but with the Complys foam tips the treble was sweet and smooth, with strong powerful bass and detailed mids. With Westone UM-56 custom tips the midrange was more present and vibrant, with a good balance between bass, mids and treble. To this day it is hard to fault the W3 with Complys foam tips or UM-56 custom tips.
 
Subsequently the Westone UM3X caught my ears, and offered a more audiophile frequency response while working with a wider variety of tips and ear canal shapes. But the UM3X had slightly less midrange warmth and a bit less depth of soundstage than what the W3 offered. Still, performance was on a comparable level, depending on your tastes, with the W3 being slightly recessed in the mids and the UM3X being slightly forward in the mids. Both IEM perform well un-amped, and scale up as the source and amplifier are upgraded. My main complaint with the UM3X was that they could sometimes sound a little congested in the mids with complex musical passages.
 
Then the Westone 4 came out, which I had the pleasure of secretly beta testing early versions through production, and they corrected most of the issues with the W3 and UM3X, which I still own and love. They brought back the larger soundstage of the W3, with the balanced bass of the UM3X, and added just the right amount of midrange presence. The problem with the W4 is that they are more laid back in the highs and less energetic in general than the others, and sometimes they need an amplifier to wake up a little better. The W4 did need a redesign of the silicone tips to sound more open and detailed, which happened after a couple of years, and the new tips took the W4 up a notch in performance (sounding slightly veiled like the HD650 with the original tips, and more crisp like the HD600 with the new tips - the comparison between Audeze LCD-2 rev1 vs rev2 could also fit here).
 
At that point I stopped looking at high-end universal fit IEM, because between the W3, UM3X, and W4 I owned three top-tier IEM that could be rotated through depending on the source, amp, and program material I wanted to listen to. Plus I had many flagship custom IEM that I would use for more serious listening.  I mostly use the universal fit IEM when I am out and about, so I worry less about damage or loss because they cost less than my custom IEM. 
 
I did get a pair of HiFiMan RE-600 as a gift, and when well amplified by the HiFiMan HM-901 with balanced amplifier, they sound very much like a well amplified Westone 4, with slightly smoother treble but otherwise similar timbre and tone. Basically I mostly enjoy the RE-600 with my HM-901, which I will occasionally use at my bedside table; but I don't feel that my iPhone or iPad properly drive the RE-600, and so they also get limited use.
 
I still own many other nice high-end IEM that I have enjoyed and didn't want to part with, but they rarely get any listening time these days, including the UE Triple.fi 10 Pro, Shure SE-530, Image X10, Westone 2, Monster Turbine Pro Gold, and HiFIMan RE-262.  Each of those has something I'd want to fix - more mids in the TF10Pro or W3, more detail in the W4 and MTPG, more bass in the W2, More treble in the SE-530 and Monster, more treble and bass in the RE-262, more efficiency in the RE-600, and less upper-bass bled into the mids with the X10.
 
So, because of my large experience with universal IEM in the past, and also with 7-8 different custom IEM ranging from low-end to flagship, I was asked last November to beta test Nuforce's new Primo 8 IEM. I've worked with Nuforce to beta test other products, and they have always been very responsive to suggestions and the final versions have always been improved and something that I would want to own.  
 
I have heard 4 different versions of the Primo 8, including the final production version, and must say that Nuforce has done a great job bringing out an audiophile quality balanced armature universal fit IEM.
 
SPECIFICATIONS & FEATURES FROM NUFORCE:
 

Model Name: NuForce Primo 8 - MSRP $499
Full Product Name (for online store): NuForce Primo 8 Phase-Coherent Quad-Speaker Earphones
Slogan: Your Personal In-Ear High End Speaker System
 
When the goal is to replicate the sound quality of reference-class, multi-driver high-end speakers in your ear, the NuForce Primo No. 8 earphone stands well apart from the crowd. To achieve this elusive goal of breathtaking realism, explosive dynamic and natural sound, the Primo No. 8 embraces patent-pending technology to capture the best of both worlds: the coherence and seamlessness of a one-driver earphone, with the detail and transient speed of a balanced armature speaker array.
 
Balanced Armature Drivers:

 

Balance armature drivers deliver the highest efficiency of any in-ear speaker design available.  NuForce has fitted the Primo No. 8 earpiece with four proprietary balanced armature speakers to form a unique 3-way design. Two units operate as one for bass frequencies, with one speaker each for the midrange and treble bands. With two speakers working in tandem to reproduce the lowest frequency ranges, the listener experiences the purest, most natural bass possible - in effect, doubling up on bass speakers reduces overall harmonic distortion by over 75 percent. The Primo No. 8’s swift, rock-solid bass operates as the foundation for dynamics heretofore available only in the most costly over-ear dynamic and electrostatic designs.  Music lovers who have used balanced armature earphones will discover that the Primo No. 8 is far more refined and coherent than anything that they have ever experienced before.  The Primo No. 8’s remarkable midrange resolution, clarity and neutrality are among its most distinctive features.
  
Patent-Pending Linear-Phase Crossover:
 
The graininess of other balanced armature earphone designs is often the result of crosstalk between drivers due to their crossover network’s inability to prevent overlapping. That is the achilles’ heel that plagues all other balanced armature earphones until now. In contrast, Primo No. 8's four-driver speaker array employs a crossover network that seamlessly distributes music’s frequency bands utilizing a proprietary first-order Butterworth filter design.
 
First-order Butterworth filter designs are not without its problems. It offers an often insurmountable challenge for home stereo speakers owing to the required power levels along with difficulties relating to off-axis performance and room interactions. As a consequence of an earphone’s far smaller size and implementation, these issues simply don’t apply. However, an obstacle that does stand in the way of the Butterworth filter used in earphones is, again, size – a lack of space for the crossover’s parts. Here’s where the Primo No. 8 shines.  NuForce has addressed the size issue by developing a proprietary first-order Butterworth crossover network requiring fewer and smaller parts than ever offered before. The Primo No. 8’s proprietary crossover design has the earphone’s four speakers singing as one.
 
While the technology is far too complex to summarize here, the results are abundantly audible. Transient speed is incredible. Plucked strings take on an amazingly life-like presence. Vocalists sound as if they are there in the flesh.  Percussion explodes in a truly three-dimensional sound field. The subtlest of details appear magical and the sound never fatigues. The audiophile can now enjoy the promise of a true linear-phase crossover design absent the drawbacks plaguing products that have employed these topologies in the past.
 
Proprietary Cable Design:
 
To achieve the Primo No. 8's unprecedented sound, nothing less than the best audio cable will do. There is more to the apparently smooth and lightweight cable than meets the eye. Inside this unique NuForce star-pattern Litz cable are several advanced technologies to achieve the most accurate sound reproduction possible.
 

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For strain relief, typically a weak point of earphones, the Primo No. 8’s cable is built around a core of Kevlar Silk.  This core is then surrounded by a star pattern of seven silver wires. A layer of insulation envelops the silver wires, which in turn is surrounded by another star-pattern of nine bundles of fine gauge, seven-stranded, individually insulated OFC wires – a technique called Litz construction. Litz cables, most often encountered in radio-frequency transmission technology, are especially effective in the delivery of high frequency signals. The entire cable assembly is jacketed in a pliable polymer to eliminate mechanical noise contamination. Taking cable design to its zenith, the Primo No. 8 employs isolated left and right ground wiring to reduce inter-channel crosstalk and maximize channel separation.
  
Maximum Noise Isolation:
 
A reference-level earphone requires ear tips that provide a good, solid seal, particularly important for good bass performance and privacy. Toward this end, the Primo No. 8 employs maximally effective Comply Isolation Foam tips.
  
The Final Word:
 
In capturing the best of both worlds – the coherence and seamlessness of a one-driver earphone, with the detail and transient speed only a balanced armature array can offer – the Primo No. 8’s innovation, performance and value are nothing short of unique. Having experienced the Primo No. 8, the listener will see that no detail has been overlooked. The NuForce Promo No. 8 earphones deliver the most natural sound that audio technology is capable of providing.
 
Additional Features:
 
Included with the Primo 8 are:
 
-        Four (4) sizes (two pairs per size) of silicone ear tips
-        Two (2) pairs of Comply Isolation foam ear tips
-        A designer carrying case
-        Two (2) sets of cables (with and without microphone)
-        Cleaning cloth
-        Cleaning tool
-        3.5mm to 6.5mm adapter

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Selling Points​

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-     In-Ear Audiophile-Quality Speaker System: Four balanced-armature drivers in each earphone deliver a smooth, extended response, explosive dynamic realism and fatigue-free sound.
 
-     Ideal Balance and Accuracy: A patent-pending three-way phase-coherent crossover design achieves perfect linear phase performance resulting in a natural, fully dimensional soundstage, lightning-fast transients and crystalline transparency.
 
-     Breathtaking Realism: A captivating midrange and delicate highs envelop the listener in musical textures almost real enough to touch.

Click to expand...

 
 
GEAR USED:
 
15" Macbook Pro Retina as transport, with CEntrance HiFi-M8 and DACport DAC/amp, Audioengine D3 DAC/amp, or iPhone 5s and iPad Air headphone out and with Pico DAC/Pico Slim amp via CCK.
 
IMPRESSIONS - HANDS ON:
 
Before I comment on the sound, I want to note that the combination of Complys foam tips, over-the-ear guides, and the rotating coaxial cable connector make it harder to get these earphones inserted without the cable getting in the way. 
 
The weight of the ear guide would sometimes cause the cable to rotate in the socket, and that often puts the guide and cable right between my ear and the ear phone, blocking it from being inserted. This usually happens because I'm rolling up and compressing the foam tip and then keeping it compressed with two fingers while inserting it with one hand, while the other hand is pulling the ear lobe back to open up the ear canal better - and so there is no extra hand left to control the cable when it decides to rotate under it's own weight.
 
My pre-production Primo 8 came with only the foam tips, but when I switched to some Westone silicone tips (old style) it was much easier to insert the IEM one handed without issues, because I don't have to use my other hand to pull my ear lobe back to open the ear canal more. So I can use my other hand to keep the cable from rotating out of place during insertion. 
 
I mentioned this to Nuforce, and suggested that a removable guide like with the Sennheiser IE8 might make more sense, or a tighter coax jack that doesn't let the cable rotate as easily. That was when I found out that the Primo 8 will be shipping with a small notch around part of the edge of the cable socket, with a small bump on the end of the cable's plug, which will engage with the notch and will lessen the chance that the cable will rotate more than 20 degrees total. You can intentionally force it to rotate farther if you want, as the plastic bump is flexible and can deform under enough pressure to rotate the cable.
 

 
 
Once the IEM are in place, with either foam tips or silicon tips, they are very comfortable to leave in for hours. I also very much like the 3.5mm plug which works with the small hole in my Apple Brand iPhone case, while others like my JH Audio custom IEM cable won't fit through the hole in my case. 
 
We discussed the possibility of a cable with microphone, and it looks like that option may become a reality. The problem is that the coaxial copper/silver combination Litz cable is actually fairly costly, as they ship the Primo 8 with what is already the equivalent of an upgraded aftermarket cable.
 
LISTENING EXPERIENCE:
 
Since these are balanced armature IEM they should not need a lot of burn-in, and with the most recent pair, which had no hours on them before I got them, I didn't hear much of a change in the sound outside of the first 24 hours - they opened up slightly in the first 24 hours with no change in sound signature. It was immediately obvious that the Primo 8 was a very detailed and well balanced sounding IEM.
 
I did most of my early listening with the Complys black foam tips that came with them (Westone compatible bores), and later as I wrote this review I re-listened to most of the music with some old style Westone grey silicone tips. I am expecting to get some Nuforce silicone tips to try later, but until then I can say they sound great with the old Westone tips which are readily available. The sound is slightly more detailed and open with the Westone silicone tips which I preferred, but the foam tips do an excellent job as well. Isolation was good with either tip.
 
I first tried them using the iPhone 5s and CEntrance HiFi-M8 digital DAC/amp, and I tried a wide variety of my favorite lossless Jazz and New Age music, and then listened to some Blake Shelton country music, Maroon 5 rock music, and some Christina Aguilera pop music. I moved on to try at least 50 different artists in a wide variety of genres, with 90% of the music in Apple lossless format as high as 24/192 bit rate. I then tried other sources like iPhone and iPad headphone out, and other DAC/amps.
 
BASS:
 
Unlike the earlier prototypes where I was often wishing for more bass impact, the final version has just enough bass to satisfy most people including me. The Primo 8 are not bass-lite or cold sounding in any way, but they are also not a bass-head's dream. The bass response is what I would call neutral.
 
It's there and present, and it's very fast and detailed, as well as very nicely extended to below 20Hz with test tones. Bass texture is excellent (timbre & tone). String bass plucks sound crisp and speedy, with the low notes keeping up with the upper harmonics. Bass drums have that nice deep bass ring, just with slightly less impact than my W4 or UM3X. I do think that the bass impact was slightly improved with the silicone tips vs the Complys foam tips.
 
I switched the HiFi-M8 DAC/amp output impedance from 1 ohm to 10 ohm and the low-end impact improved a little more, so I left it there. It wasn't necessary to use the bass boost switch, although the Primo 8 were able to handle the bass boost very well without being overdriven at high volumes. My DACport also has a 10 ohm output impedance, and the Primo 8 sounded good with that as well.
I also tried the iPhone 5s headphone jack, and thought this had a little better bass impact than the HiFi-M8 at 1 ohm output, although the 5s is not as clear and spacious sounding in return. So source and amp choice will make a difference, and the Primo 8 scale up very nicely but don't require an amp. ** 
 
** Note - The iPhone 5s headphone jack also sounds a little more forward in the mids when compared to the HIFi-M8 or Pico DAC/Slim with a CCK, and you definitely benefit from adding a DAC/amp to the iPhone 5s when trying to wring out the most from any IEM. Changing to the Macbook with most any DAC/amp confirmed that the iPhone 5s headphone jack is lacking the detail, freq balance, and space of a nice DAC/amp. If listening un-amped I would prefer to use my iPad Air which sounds smoother and more detailed than the iPhone 5s.
 
Anyway, I don't consider myself an exclusive bass-head, as I can enjoy neutral and spacious sounding headphones like Sennheiser HD800 and Stax SR-009. Some would say that these two headphones are bass-lite, but when the SR-009 are driven by a Blue Hawaii amp or the HD800 are driven by an EF-6 amp then they cannot be called bass-lite. 
 
Yes, headphones with really strong bass are a lot of fun, but it can be a problem if the headphones add more bass than what the recording calls for at the time. The HD600, HE-500, or LCD-2 rev2 are other example of headphones with a good balance between bass, mids, and treble, and they are less picky about what amp you pair them with to get strong bass out of them (vs the HD800 or SR-009). 
 
So I played some music looking for ways to characterize the Primo 8 vs those two full-size flagship headphones, and one particular track was Ryan Adams "Dirty Rain" where it opens up with an acoustic guitar and then after a few seconds the bass guitar comes in, and after that the drums rise to a slow beat. I was able to place the singer at front center stage with the drums just behind him, with the acoustic guitar off to the left and slightly behind, and the bass player slightly to the right, with the piano farther back and more to the right. 
 
The bass guitar and bass drum were present and accounted for, and although they wont make your ears rattle they did offer a deep bass foundation. In fact, all the different instruments and vocals seemed to be at similar levels to where I expected them to be, having listened to the same songs with the HD800 or SR-009. Some IEM like the V-MODA Vibratto can exaggerate the bass too much, and generally sound less accurate or muddier, with recessed mids in relation to their bass. That puts the singer further back, and almost on top of the bass drum behind him. 
 
I also could not place the location of the bass guitar with the V-MODA at all. It was like having a "bass cloud" surrounding me with the V-MODA. The Westone 3 also made the bass player a little more difficult to locate than with the Primo 8, although the bass speed/detail was much closer to the Primo 8 and a big step up from the V-MODA.
 
I switched to electronic music with the Primo 8, including Infected Mushroom "Dancing with the Kadafi", and the music surrounded me from all directions during the intro, and then when the bass synthesizer kicks in around 1:20 I could feel the pulsing rhythm with decent impact (same thing with some Lindsey Stirling electronic music, and others). No, these wont hit you like a V-MODA, Westone 3, UE11Pro, or JH16Pro, but there really isn't anything really missing down there either. 
 
Would I say that the V-MODA or Westone 3 are a little more fun with bass heavy electronic music like Infected Mushroom? Sure, but when it comes to actual acoustic instruments and vocals the Primo 8 leaps ahead. The Primo 8 did sound punchier with electronic music as volume levels went up, but then that could become harmful to your hearing with longer listening sessions. Speaking of volume, I'm finding that they are a little more efficient than my Westone 4 as well.
 
MIDRANGE:
 
In general, the timbre and tone of the Primo 8's midrange is spot on. The Primo 8 has a slightly more forward or slightly more aggressive midrange in comparison to the W4, so loud listening isn't always appropriate with all music choices. Pianos sound lovely with the Primo 8, but if you crank them up too loud in order to enjoy the string bass more, then the piano might occasionally start to intrude too much. 
 
I'm not saying that the midrange is aggressive per se, but rather it's that way in comparison to the more laid back Westone 4, and in relation to their bass output. If I try to remove anything in the midrange via EQ then something sounds like it's missing. It's better to add 2-3dB of bass than mess with the wonderful midrange, but 99% of the time I use no EQ at all to listen to these (but an amp with 10 ohm output impedance helps).
 
In direct back to back comparisons, even when amped the W4R can still sound a little less energetic and less exciting after having just heard the Primo 8. The W4 mids can also sound a little less rich and engaging in direct comparison. However, switching between these IEM is a slow process as the combination of the ear guides and the rotating cable jack makes it hard to insert the Primo 8 quickly. Plus I have to take time to unplug the IEM from amp and plug in the next one, and then volume match them. This slower process makes the memory of the previous IEM's sound fade a little, and complicates making impressions with back to back comparison.
 
Regardless, midrange clarity and vocal presence is very good, like the singer is in the same room with you. The Primo 8 seemed to do a little better job with male or female vocals than most of my other top tier universal IEM. The realism does improve as source and amp improve, and the midrange of the iPhone 5s built-in amp is not as good as that of the DAC/amps that I used (or even my iPad Air). Nevertheless, they are still very enjoyable un-amped.
 
However, with some songs via iPhone 5s headphone output, such as Maroon 5 "Payphone", the upper-mid/lower-treble could get slightly fatiguing, due to the combination with a less than perfect built-in amp. Basically you can hear the colorations in the iPhone 5s amp easier with the Primo 8, as they are not what I would call a very forgiving IEM. They show you just how good the mastering or the source and amp really are.
 
For use with the iPhone 5s I tried subtracting about 1.5-2 dB at 6Khz and that helped with this song, although it's not needed when using DAC/amps such as the HiFi-M8. And it's not needed with all songs via the iPhone headphone out, just some recordings. And I don't feel like the Primo 8 actually has a bump in the frequency response at 6Khz, because they don't seem to exacerbate sibilance. For example, with Diana Krall "Temptation" the song can sound sibilant with many headphones but not at all with the Primo 8. So this was clearly more of an issue with the iPhone's amp than with the IEM.
 
TREBLE & EVERYTHING ELSE:
 
The Primo 8's treble is smooth and extended. How extended I can't say because my 51 year old ears roll off a lot by 12Khz, and I have to turn the volume up a little with any headphone in order to hear the 16Khz tones. But 16Khz tones are as audible with the Primo 8 as they are with my other phones.
 
The W4R being a little more laid back or "mellow" sounding can make them feel a little more refined in the treble at times, but the Primo 8 don't seem to have any high-end grain. And they are transparent enough that they just seem to disappear at times.
 
Cymbals have great timbre and tone, with proper decay, and snare drums sound real rather than sounding plasticky or like an electronic drum machine. The treble detail and extension offers a great sense of air, ambience, and space with recordings; so even with the Primo 8's slightly forward mids the venue doesn't ever become small. Only your placement in relation to the performers is affected.
 
The W4R's less forward mids can make them seem a little more spacious than the Primo 8, but also slightly less intimate. Again, I'm not saying that Primo 8 have a small soundstage, but it's not exactly what I would call "holographic 3D surround sound" although the stage imaging is very precise with a wide stage. 
 
I would say that the Primo 8 seem to put me on the 1st or 2nd row of the venue or auditorium, instead of 5-8 rows back like the W4 (but not on stage either). The W3 might put you even further back, while occasionally the Westone UM3X would put me on stage. The ambience from a live venue such as with Eric Clapton "Unplugged (live)" is actually quite good, lending to the realism of a large venue with a more intimate seating placement. 
 
SUMMARY AND OTHER THOUGHTS:
 
People are always asking me, which universal IEM is best, or which one should I buy if I can only buy one. And my answer is usually there isn't one best headphone, but there's usually 2 or 3 complimentary ones that cover all the bases. As good as the HD800 or SR-009 are, they are complimented by also having an HE-500 or LCD-2 to rotate with them, maybe adding in a nice punchy closed headphone that isolates a little.
 
The same goes with IEM or earphones. And just like how different earpads or changes in fit on a headphone can change the sound from one person to another, so can the different IEM tips or changes in depth and position in the ear canal affect the sound.
 
So, what I hear with these IEM may not be what you hear. If I tell you what IEM to buy as your "one and only precious", there is a good chance that you will be happy and offer praise, and also a good chance that you will be disappointed. If I offer praise for an IEM and it doesn't sound that way to you, then you either have to change your tips, the positioning in the ear canal, your source/amp, or chalk it up to a difference in personal preference.
 
I want to make it clear that the Primo 8 is a very transparent sounding IEM, without disturbing colorations or veil over the details. Vocalists and instruments are "lifelike" and natural sounding. Often I listened to an entire album when I should have been doing individual song comparisons, forgetting that I was supposed to be evaluating their performance. They don't make it easy to get much work done while listening to them. 
 
I really want to avoid calling them analytical, because some people would interpret that to mean they are cold or clinical, or without heart and soul. That couldn't be farther from the truth. But they certainly can be used to pick out details that may be skimmed over by other IEM. I don't think anyone would argue against these statements, but personal preference can influence how much one enjoys these traits.
 
In my case I think the Primo 8 are a great compliment to my Westone 3 or W4R (now the W30 and W40), or any other top-tier IEM with stronger bass. If I want to rock out to classic rock or electronic music I can go for the extra bass of the W4R, or even more bass with the W3. If I want to rotate to an IEM with a more laid back presentation then it may be the W4R over the W3, although the W3 still make a good low-volume/laid back IEM when used with Complys foam tips. But if I want to listen to a more balanced, detailed, transparent and realistic or lively presentation then I can pull out the Primo 8 as my first choice. This is where they really shine.
 
The Primo 8 are sometimes reminiscent of the Westone UM3X but as an upgrade, where they actually remind me more of my Westone ES3X custom IEM in terms of timbre and tone. I've always said that my ES3X were a great compliment to my Westone ES5 or JH16Pro custom IEM, which offer a little more warmth and impact. The ES3X have a similar life-like and detailed midrange with an energetic sound signature, although they also have a little more bass impact and larger soundstage - not surprising in a $800 multi-bore custom IEM vs a single bore universal fit IEM. In my ES3X review I also compared them to the HD800, for their similar sound signature.
 
In addition to audiophiles, I'm certain that there would be a large number of people out there that would want to use the Primo 8 as a neutral studio or on-stage monitor. Many other universal fit IEM don't have enough midrange to serve in that role, or they may offer a bit too much midrange to be enjoyed as much by audiophiles.
 
MORE ABOUT THE COMPARISONS:
 
As I mentioned before, the W4 and RE-600 are well balanced sounding competing IEMs that sound similar to each other with a good quality amp, but the RE-600 can only keep up with the Westone 4 if the RE-600 are amplified and not driven right out of the iPhone headphone jack. Using a HiFiMan HM-901 digital audio player, the W4 and RE-600 sound almost the same but with a slightly smoother treble in the RE-600 while there is an extremely slight grain to the W4, heard only in direct comparison.
 
The problem is that without amplification the RE-600 have less bass impact than the Primo 8, and the un-amped RE-600 sound fairly bland or lackluster in comparison. So, if both are un-amplified via iPhone headphone jack I would pick the Nuforce Primo 8 every time, although I'd still prefer to use my iPad Air. When I do add that extra little bit of bass (1-2dB) with an equalizer app, I can listen to the Primo 8 un-amped for hours and hours on end, with any genre or artist - it brings them closer to that "one and only precious" that I mentioned before. 
 
Up until now the Westone 4 with their newer "Star" silicone tips were my preferred universal IEM because they have good sonic balance, strong bass, natural vocals, and a large soundstage while using the standard tips that they ship with. The W4 (W40) are one of the more accurate universal IEM on the market, but they can feel slightly veiled sounding vs a few other top tier IEM, making the W4 a little less exciting sounding than the W3 (W30). I was very happy with how well the W4 perform unamp'd with the newly designed stock tips, so it was a real eye opener to compare them to the Primo 8 and hear even more clarity and detail.
 
Nevertheless, I will not attempt to clearly rank the various universal fit IEM I've tried as being #1, #2, and #3 etc. That's very difficult because some IEM do certain things better than others, but then they lack in another area where their competition succeeds. I could go on and on about each and every universal fit IEM that I've owned or tried, about what I would change about them if I wanted to (I actually have that written up, but this isn't the time nor the place for that). So which IEM is #1 depends on what's more important to you.
 
FINAL CHARACTERIZATIONS AND RECOMMENDATIONS:
 
The Primo 8 have the overall detail of the W3, without the recessed midrange of the W3 or the slightly veiled midrange of the W4. The Primo 8 have a more crisp, detailed, engaging and lifelike midrange than the W4, but the mids can occasionally be a little too present and forward like with the UM3X (although the Primo 8 mids are more transparent). Basically, the W4 midrange levels are more balanced in relation to their bass and treble than the Primo 8 (more) or W3 (less).
 
When comparing the bass response and impact, the W3 might overdo things a little, while the W4 bass is just right, and the Primo 8 seem slightly weaker in their bass impact in comparison. On it's own, the Primo 8 is not a bass-lite IEM and the bass is fast, tight and extended. But the Primo 8 sometimes leave me wishing that I could crank up the volume for a little more bass impact without the mids becoming too loud at the same time.
 
The treble of the Primo 8 seems just right, while the treble of the W4 can be a little muted or muffled at times, and the treble of the W3 can be slightly hot or boosted when used with the wrong tips (grey silicone or triple flange). With Primo 8 the cymbals sound crisp and metallic, with better air and extension than the W4 and smoother than the W3. String instruments have the proper amount of texture in the bow on string, and voices do not become sibilant.
 
So, what does a person do when they like three or four different top tier IEM, but one is most balanced and detailed in the treble and midrange, another is most balanced sounding in the midrange and bass with slightly less detail, while the third has the best bass of them all but requires expensive custom fitted tips for the mids and treble to keep up, and the fourth requires an amplifier to keep up?
 
Well, I would tell a "bass-head" that W3 is #1 but they should only be used with Complys tips or UM56, since they can become slightly recessed, fatiguing or bright sounding with silicone tips. I would tell someone that W4 is #1 if they want a neutral monitor with strong bass at the expense of a slight decrease in midrange and treble clarity and openness. I would tell someone that Primo 8 is #1 if they want a warm and more energetic sounding neutral monitor, with the clearest vocals and instruments and a very open and transparent sound, as long as they don't need a higher-than-average or "boosted" level of bass impact. 
 
In my case, I've pretty much moved on to high-end custom fit IEM for any serious listening at home, and I use my universal fit IEM for traveling to places where my IEM might get lost, damaged, or stolen. I don't want to be roughing it when I'm mobile, and with the Primo 8 I don't have to.

RSA F-35 Lightning
 
HISTORY:  My first portable headphone amplifier was the Ray Samuels Tomahawk in 2007.  I needed it because my Shure E4c were not very efficient and needed more power to wake them up or energize them, and my Sennheiser HD600 were much more demanding and needed significantly more power than my iPod could supply - without the amplifier the HD600 felt dull and bland, while the E4c lacked impact and dynamics.  An amplifier transformed them both, and thus began my Head-Fi journey.
 
Since then I have grown to appreciate what a good amplifier can do for my listening enjoyment, especially with full size headphones designed for home use.  I have owned and heard dozens of different portable amplifiers, and even went on to do a review of 13 different portable DAC/amps a few years ago before I settled on my favorite pairing of Pico DAC, DACport, and Audioengine D3 as sources + the RSA SR-71b and Pico Slim as my two main portable amps).  I would use the Pico slim with just a small iPod Nano, or the Pico DAC+Slim with an iPad camera connection kit, the DACport or more recently the D3 for most headphones on my Macbook, with the SR-71b added into the mix for the more demanding full-size headphones.  Most of the other portable gear has fallen by the wayside.  I don't recall the last time I used my Meier 3MOVE or Headsix, iBasso D4, or Practical Devices XM5. And many others that were not as unique have been sold a long time ago.
 
Portable headphones often sound good without an amplifier when used with a decent portable music player, but even then it was easy to observe that adding an amplifier to most portable gear would provide an upgrade in sound quality, even in cases where the extra power was not needed. A lot of gear has a nicer sounding line-out than the headphone out jack, so an improvement (quality) could be realized by adding an amp, even if you didn't need more power (quantity).  Only in the past couple of years have we begun to see portable DAPs that have both excellent sound quality and power output levels; but these can cost as much as $1000 or more, and may require additional time to convert your music into the proper format when you already have it all loaded onto your iPhone or iPad in Apple Lossless format.
 
The challenge with many portable amplifiers is that they often run at 5 volts and didn't have enough power to do justice to full-size non-portable headphones such as HE-500 and LCD-2 orthodynamics.  And they may not have enough voltage swing to properly drive the high impedance HD600 and HD800.  They still improved things over the headphone out of an iPod, but they didn't rival desktop amplifiers. When traveling or mobile, it was difficult to get the full desktop rig experience in a small travel bag or backpack.  A few years ago only an occasional portable amp could manage to do that, such as the Meier Corda 3Move, Meier Stepdance, or balanced RSA Protector.  When these portable amps came out and could drive these difficult headphones it was a revelation, albeit with some compromises here and there.
 
When the RSA SR-71b came out it blew everything portable out of the water when using the balanced output.  Although the 1/8" jack was not quite as detailed, open, airy, or spacious as the RSA P-51, the balanced output was noticeably ahead of the P-51 in power and punch with a similar level of transparency.  Single ended is very good, but not exceptional like the balanced output.  Via the balanced output I considered the SR-71b to have sound quality on par with some more expensive desktop amps like my maxed Woo WA6, ALO Amphora, CEntrance DACmini and HiFi-M8, or Nuforce HAP-100.  And amazingly the SR-71b sounded better with my HD800, while packing more punch with my HE-500 and LCD-2.  To have more power coming out of a portable amplifier than some well respected desktop amps was unheard of, and to match the sound quality was just as impressive.
 
Over the years of ownership of the SR-71b I found that I was not using the 1/8" output at all, which meant wasted space on the front panel.  Ray Samuels apparently also found that many people using portable amps with 1/8" outputs were mostly using portable headphones, and that most people using the SR-71b were using full-size balanced headphones.  So he developed the F-35 Lightning that was smaller and more convenient to carry, while packing a similar punch to the larger SR-71b with the majority of popular full-sized headphones.
 
FEATURES:  The F-35 lightning gives up the 1/8" jack that I wasn't using, which allows it to be lighter and about 2/3 or 3/4 the size of the SR-71b.  It still offers the glowing red power switch, balanced output, three levels of gain (3,6,21), single ended or balanced inputs, built-in rechargeable battery, and a 3 year warranty (1 year warranty on the battery).  The charger is also 8.4v instead of 16.8 volts.  I have never tested the battery life, but I have used both amps all day long and not had to plug them back in to charge before I was done listening for the day.  
The Lightning is a dual-mono design, and in balanced mode the right channel and left channel are completely independent.  The single ended input uses a phase splitter to convert the signal into a balanced signal, and there is very little difference in sound with the two inputs if the source is just as good via either SE or balanced.
 
GEAR:  I used an iPhone 5S and Macbook Retina Pro as music transports.  I used an Apple camera connection kit with Pico DAC or the CEntrance HiFi-M8 as sources for the iPhone 5s digital audio.  For the Macbook I used the PS Audio Perfectwave DAC Mk2 or Stello DA100 Signature for their balanced outputs, plus the Audioengine D3 or CEntrance DACport as portable laptop 24/96 sources to feed into the F-35 Lightning.  I used an ALO jumbo Cryo Silver mini-mini interconnect for single ended input from the portable DACs, and a Moon-Audio Silver Dragon balanced input cable from the balanced desktops DACs. 
 
I used several headphones for testing, including JH Audio JH16 Pro Freqphase with a balanced TWag II cable, HD600 with a balanced APureSound V3 cable, HD800 with a balanced Moon-Audio Black Dragon cable, HiFiMan HE-500 and Audeze LCD-2 rev2 with a Silver Dragon cable, and HE-6 with a stock HiFiMan PCC-OCC cable.
 
SOUND:   The sound quality is quite good by any standards, portable or desktop.  With your eyes closed you simply would not know that you are listening to a portable headphone amplifier.  With IEM the Lightning has a completely black background with no hiss, and good channel balance at low volumes in low gain.  In medium gain the left channel comes in a little sooner than the right, but good balance is still achieved at fairly low volumes on the volume pot.
 
When compared to it's more expensive sibling, the SR-71b, the F-35 Lightning is only slightly more forward sounding but never in your face or too upfront.  The micro-detail, ambience and air is just as good, so a large venue or large space is not lost on the listener - only the position relative to the stage changes between the two amps.  The F-35 might be closer to the front row seats than 5-10 rows back like the SR-71b or ZDT desktop amps.  This makes the F-35 sound slightly more involving and vivid at times, and sometimes more intimate too.  
 
But it never pushes you up onto the stage, and never sounds closed in with any headphone - the Lightning typically offers a good sense of depth, imaging and separation. The soundstage is only as large as what the headphones you're using can offer, but even when switching from the HD800 to the HE-500 or LCD-2 rev2 the soundstage never becomes too forward or artificially small.  You only hear that slight change in position to the musicians when you switch back and forth between this amp and the SR-71b or EC ZDT desktop amp; and without a direct comparison you might not ever know what you are missing, which is not much at all.  
 
The bass seems to have slightly more mid-bass bloom and a slightly warmer lower midrange than my SR-71b, but the sound never becomes thick or troublesome.  This is especially beneficial for headphones that have more of a tilt towards the high end like HD800, to give the instruments the proper weight and feel that they deserve.  I've found it difficult to enjoy the HD800 with my Woo WA6 when it's got the right tubes installed for everything else, because the combination doesn't help the instruments feel solid and present.  I feel the same way with the DACmini, where the HD800 can sometimes feel more fatiguing in addition to lacking some weight.  The HiFi-M8 is a definite improvement with HD800 over the DACmini, but still not optimal like the Lightning.
 
But I'm listening to the HD800 right now via F-35 Lightning and balanced Perfectwave DAC, and I don't think anyone would ever complain that the HD800 are bass-lite or rolled off with this amplifier.  Sure, the HD800 still don't have the impact of the LCD-2, but the HiFiMan EF6 is my only amp that can get the HD800 closer to the LCD-2's bass.  The reproduction of string bass in jazz music is very fast with great texture, and with electronic music it throbs and surges as it should.  With Infected Mushroom the bass reproduction from my HD800 is just as strong via the Lightning as it is with my Eddie Current ZDT desktop amplifier!  Switching to the LCD-2 brings the bass output to a whole new level - my vision is rattled and blurs by the time I can hear distortion as I crank it up to dangerous volume levels. 
 
The midrange sounds rich, vibrant and life-like.  I don't think I would change anything there.  There is no suck-out anywhere, and it handles male and female vocals equally well.  Pianos are very dynamic and realistic without ever sounding hollow, and saxophones sound rich and breathy.
 
The treble response with the F-35 Lightning seems to be just as refined as with the SR-71b and is never sibilant.  Nor does it make the HD800 sound etched or fatiguing as many amps are prone to do. The Lightning renders cymbals and snares with a realistic shimmering timbre and tone, with good extension.  Guitars and strings are crisp and detailed, and electric guitars are crunchy and scratchy when called for.  Neither amplifier could be called bright either, and in fact the F-35's treble is very slightly muted in presentation when compared with the DACmini or HiFi-M8.  However, I would also never call the F-35 dark sounding or rolled off - it sounds good with HD800 and LCD-2 alike, although with slightly less treble presence than my DACmini or Eddie Current ZDT desktop amplifiers. Again, something you wouldn't have considered on it's own without having done a direct comparison, and a simple switch of tubes to a TungSol 5751 will bring the ZDT's treble in line with the F-35.  So, there is no fault there either.
 
POWER:  Good bass impact is often associated with amps that offer higher power output, and while the F-35 lightning cannot drive the very inefficient HE-6 to the same high volumes as the SR-71b, it does to drive the HD800, LCD-2 and HE-500 to insane volumes before hearing any distortion.  Maximum volume can be reached in medium gain with a strong balanced source, and high gain is only needed when using a weak source like an iPod line-out.  Overall it's maybe only about 3-4 dB (maybe 5) less powerful than my SR-71b or ZDT before the LCD-2 start to show distortion. That makes the Lightning quite a bit louder than the Pico Slim, or even the RSA Tomahawk, P-51, and Protector that I used to own.  The Lightning will cause permanent hearing damage if you don't monitor your listening volumes and duration properly - I'm pretty sure that I briefly hit 120 dB several times with each headphone, although I tend to listen at less than 90dB (I have a Radio Shack dB meter that I've used in the past).
 
SUMMARY:  The fact that I can even compare the Lightning to my $2700 ZDT side-by-side and still enjoy it this much is a testament to how good this little amplifier is.  Does it sound like a $2700 amp? No. But neither is it put to shame by the ZDT when driven by a high-end balanced DAC.  This is an amazing portable amplifier.
 
This is an amplifier that I can pair with a high-end source and full-size headphones, and it scales up to perform at a level you'd expect from a more expensive desktop amplifier.  Even when paired with my new HiFi-M8 it offers slightly more power and increased synergy with HD800 in a small portable package.  And it sounds quite good with a budget portable 24/96 USB DAC/amp such as the D3 or DACport as the source (used as a pre-amp).  The DACport and Audioengine D3 sound fantastic for the price, and they go everywhere my Macbook goes, but adding the Lightning between the DAC and the headphones takes them to a whole new level with full-size headphones and IEM alike.
 
If a person already has a nice portable amplifier with single ended output but find that they don't have enough power for their more demanding headphones, I would skip the SR-71b and go for the less expensive F-35 Lightning with a re-cable or re-termination of the stock cable, assuming that you aren't crazy enough to be driving the HiFiMan HE-6 in a portable rig.  I just don't see the benefit to a portable HE-6 over the HE-500 or LCD-2 rev2, but you can still enjoy the HE-6 at moderate volumes with the Lightning if you must (i.e. louder than average).  Moon-Audio makes a wide variety of cables compatible with the Lightning's balanced output, including short adapters to convert the Kobiconn 4-pin jack to a mini-XLR, 4-pin full size XLR, or Dual 3-pin balanced jacks if that's what you use on your headphones.  Other cable makers like Ted The Cable Pro are following suite.  I think it costs about $150 shipped for a three foot balanced Silver Dragon input cable.
 
If a person wants to save money on a desktop rig because they also need to be portable, pairing the Lightning with a good quality DAC or DAP is a reasonable way to go as well.  If you need a portable DAC to feed into the Lightning, the tiny Audioengine D3 is hard to beat, and it can drive most headphones after you've run down the battery on the Lightning.  And if you need a portable amp that has good synergy with the HD800 I would highly recommend the Lightning, although it's just as good with phones like HD600, HE-500 and LCD-2.  It can be difficult to find the right amp for the HD800 that also sounds good with everything else, without making the HD800 fatiguing after long listening sessions.  My Pico Slim sounds great with the HD800, but it doesn't have the voltage swing to do them justice.
 
The only person who might benefit from the SR-71b over the F-35 Lightning, other than the insane HE-6 user, is someone who needs to drive single ended portable headphones but cannot afford both a single ended amp and the F-35.  However, there are affordable single ended amps that will sound a little better than the SR-71b in single ended mode - so the Lightning plus a smaller single ended amp would be more rewarding for most audiophiles, although a little more expensive than the SR-71b alone.
 
I rated the Lightning as a 10/10 for Value and Quality.  I gave it a 9/10 for Audio Quality, but would have picked 9.5 vs other portable amps if that was an option.  I also gave it a 9/10 for Design, partly because the headphone cable blocks access to the gain switches when it's plugged in - I would have liked to see the output jack closer to the side of the face-plate so that the gain switches could be next to the power switch.  This would have also made it easier to turn it on and off when a headphone is plugged in, if you have fat fingers.  Likewise, the input switch and single ended input are covered by the balanced input cable, so you can't leave it connected to both sources and switch back and forth. I understand that some features are dictated by the requirements of the PCB layout on an amp this small, and there are limited choices when implementing the design, so it didn't get a 7 or 8 for that reason.
 
(I'll come back later and post some photos of the F-35 Lightning next to the iPhone, D3, SR-71b, PIco Slim and HiFi-M8)

THIS REVIEW MUST BE PREFACED BY MY DAC-100 IMPRESSIONS, AS THE HAP-100 IS VERY SIMILAR TO IT BUT YET REPRESENTS FURTHER IMPROVEMENT OF THE DAC-100 AMP SECTION IN SEVERAL WAYS AS DESCRIBED BELOW.
 
See the following link for my DAC-100 impressions in the DAC-100 announcement thread from Sept 2012:  
http://www.head-fi.org/t/615533/nuforce-dac-100-news#post_8694564
http://www.head-fi.org/t/615533/nuforce-dac-100-news/15#post_8702583 - update
http://www.head-fi.org/t/615533/nuforce-dac-100-news/15#post_8705099 - summary post with everything previously posted in it
http://www.head-fi.org/t/615533/nuforce-dac-100-news/30#post_8825445 - added LCD-2 rev2
http://www.head-fi.org/t/615533/nuforce-dac-100-news/45#post_8851848 - clarifications
http://www.head-fi.org/t/615533/nuforce-dac-100-news/60#post_8874129 - clarifications - can also cont reading all of DAC-100 thread for a few tidbits here and there
 
See the following link for my DAC-100 Impressions in the HD800 thread (for good synergy):  
http://www.head-fi.org/t/426508/sennheiser-hd800-appreciation-thread/5040#post_8601885
 
 
I started with the DAC-100 last July and had posted impressions in the Nuforce announcement thread, where I posted very similar things to the review that Project86 posted recently.  The DAC-100 is a near perfect match for the HD800, driving them better than my DACmini or maxed Woo WA6.  I typically don't enjoy the DACmini nearly as much with HD800, and the tubes I have to put in the WA6 for the HD800 don't work as well when using any other headphones.
 
Still, the Nuforce DAC-100 drives the LCD-2 and HE-500 about as well as the WA6, but neither amp is as punchy as the DACmini with those phones.  The Nuforce DAC section seems to be on par with that of the DACmini and Stello DA100 Signature in overall performance, but not as smooth as the Stello.  Like the DACmini, the DAC-100 is more detailed than the Stello or more revealing, but the Stello is more forgiving of poor source material.  The Stello USB input is also not nearly as good as the Nuforce or DACmini USB input.
 
The DAC-100 is good enough that I'm using it as my primary source in the bedroom rig, and feeding the RCA output into my HAP-100 (with the HAP-100 RCA out feeding the DACmini, and then feeding the DACmini output into the WA6).  But, I haven't turned on the WA6 or EF5 amps in weeks.  I mostly use the DAC-100 for source and directly driving HD800, or the DAC-100 for source plus the HAP-100 or DACmini driving the LCD-2 and HE-500 or IEM.
 
I also found that the DAC-100 high noise floor could be an issue with very sensitive low impedance phones like V-MODA M-100 and D7000.  As for the level of engagement of the midrange, it's not bad at all in the DAC-100 but the Nuforce HAP-100 amp paired with this DAC does have a more involving midrange, along with lower noise floor and a bit more power.  With the HAP-100 added I don't really need the DACmini or WA6, but I do still use them for IEM; and I sometimes enjoy the slightly more engaging mids of the DACmini or WA6 at times.
 
As a DAC/amp combo I prefer the DAC-100 to my old Apogee Mini-DAC which had a slightly aggressive sounding flat soundstage headphone amp, but an excellent DAC.  I found even a $180 Travagans Red amp to be an upgrade over the Apogee headphone amp, which still worked well enough with high end Grados and HD600. I'd still prefer to use an external amp with the DAC-100, but with HD800 that isn't necessary and with many other popular orthodyamics the external amp is still optional.  The only thing that is an absolute NO with DAC-100 are all my IEM (hiss), and HE-6 (power).
 
[size=10.5pt]Nuforce HAP-100:[/size]

 

[size=10pt]I'm feeding the DAC-100 into the HAP-100, but looping out into the DACmini (and looping out of the DACmini into my WA6 or SR-71b amp for IEM).  Crazy, but it's a good way to quickly compare the output from each of these amps with one source.  I'm using ALO SXC interconnect cables or similar quality for my connections, and a Nuforce brand USB cable.  My transports were a retina Macbook Pro via USB, a Nuforce iDo with iPod Nano via coax, using lossless music in 16/44.1 and 24/96, and a Nuforce CDP-8 CD Player with Coax and RCA outputs.[/size]

 

[size=10pt]HAP-100 FEATURES - $595 MSRP:[/size]
 

[size=10pt]§  [/size][size=8.5pt]A preamplifier stage providing 5dB of gain with zero negative feedback for fatigue-free listening[/size]
[size=10pt]§  [/size][size=8.5pt]A single-ended Class A headphone amplifier stage (a design topology long held by audiophiles to be the last word in headphone reproduction)[/size]
[size=10pt]§  [/size][size=8.5pt]Top-grade relays for input selection[/size]
[size=10pt]§  [/size][size=8.5pt]A linear power supply employing a toroidal transformer, large capacitor reserves and high-speed regulation for fast, clean power to all circuits[/size]
[size=10pt]§  [/size][size=8.5pt]A signal-to-noise ratio in excess of 100dB[/size]
[size=10pt]§  [/size][size=8.5pt]THD+N = 0.002%, assuring the ultimate in accurate reproduction[/size]
[size=10pt]§  [/size][size=8.5pt]Four low-noise, stereo RCA inputs[/size]
[size=10pt]§  [/size][size=8.5pt]One RCA stereo output offering a full 7.8Vrms to effortlessly drive any amplifier. This output can be turned off (by pressing On and then Input buttons on the remote control) while the 6.3mm headphone output remains enabled.[/size]
[size=10pt]§  [/size][size=8.5pt]A front-panel 6.3mm jack for large, over-ear headphones[/size]
[size=10pt]§  [/size][size=8.5pt]A stylish three-digit display (setting 1 for input selection / settings 2 and 3 for output levels from 00-99)[/size]
[size=10pt]§  [/size][size=8.5pt]A full-featured remote control[/size]
 
 
 

[size=10pt]The DAC-100 and HAP-100 have a nice symmetry when stacked together - both have the volume knob on the right of the front panel, a 1/4" headphone jack on the left, and in the center of the front panel they have indicators for which input is selected.  They differ in how the inputs are selected - the input of the DAC-100 is selected by pressing a different button on the front for each input (USB, coax x 2, optical), while quickly pressing in the volume knob on the HAP-100 will cycle through one of the four analog inputs with each press.  A press-hold-release on the HAP-100 volume knob will put it into standby mode after you release the volume knob.  However, a quick press-release on the volume knob on the DAC-100 will put it in standby mode.  The HAP-100 also has a digital display for the volume level 0 - 99.  [/size]

 

[size=10pt]Both the DAC-100 and HAP-100 use a standard IEC cable for power, with an internal power supply and a power-on switch next to the IEC input on the back.  They both have an RCA output, in which the output level is controlled by the digital volume pot.  Both units have a slight wobble to the volume knob when intentionally wiggled, a normal consequence of using a digital rotary encoder.  Otherwise they feel solidly built.  They also both run a bit warm, due to the class-A biased circuitry inside.  The rubber feet are short, but tall enough to allow air to circulate between the units when stacked.[/size]


 
 
 
 
 
 
[size=10pt]After a few hundred hours of burn-in I was more confident in where the HAP-100 has some small differences in it's capabilities and strengths over the DAC-100's headphone amp. [/size][size=x-small] I found three most noticeable differences in sound vs the DAC-100 that stand out for me - namely more power, more detail, and less [/size]noise.  Those don't really change the timbre and tone much between devices, but a fourth area may be in the sense of a slightly more forward midrange that can affect synergy a little vs the DAC-100.

 

[size=10pt]First off[/size][size=10pt] - as discussed before on the forums I find that the HAP-100 has a bit more power and impact than the DAC-100 with the LCD-2 rev2 or other low impedance headphones, although the DAC-100 is pretty good with the Rev2 as well.  My LCD-2 rev2 pair better with both Nuforce amps than my previous LCD-2 rev1, and I don't find the Rev2 to be as underpowered with the DAC-100 as the Rev1 were (or HE-500).  I am so glad that I upgraded the LCD-2 to the more recent model, which pairs well with more amps.  With double the voltage swing of the DAC-100, the HAP-100 can better drive less efficient headphones too.[/size]

 

[size=10pt]But with my sensitive 300 ohm HD800 the extra power really doesn't make a big difference, and then the two amps sound more alike than different.  However, with the LCD-2 rev 2 or HE-500 headphones the HAP-100 has a bigger advantage.  For most listening, I'd be fine with just the DAC-100 to drive my HD800 and LCD-2 rev2 if I couldn't add an external amp.  For HE-500 and for IEM I'd be looking for an external amp, and the HAP-100 is a good contender.[/size]

 

[size=10pt]If not maxing out the volume on the DAC-100 when it's being used as a source-only for the HAP-100, with any given volume level out of the DAC-100 headphone jack the HAP-100 volume must be set to 88-90 on the display in order to match the volume of the DAC-100's headphone jack.  At 88-90 out of 99 max I can swap the headphones between the DAC-100 and HAP-100 and have the volume matched.  This still leaves room for the HAP-100 to be turned up to 99 and reach much louder volumes than the DAC-100 can achieve.[/size]
 
[size=x-small]While the DAC-100 output and power[/size][size=small] levels s[/size][size=x-small]eem to be on par with my maxed Woo WA6 (less than half a watt), that's only just enough to get decent performance from an LCD-2 or HE-500, [/size]although [size=x-small]being more than enough power for more efficient phones like Grado HF-2, HD800, D7000 or V-moda M-100.  But the HAP-100 power level seems to come closer to the DACmini's 1.5 watt output, and you can't max it out with most phones.  It's at least 2-3x more powerful than the DAC-100.[/size]

 

[size=10pt]Secondly[/size][size=10pt] - while using the DAC-100 as the source for everything I found the HAP-100 headphone output has a little bit more detail and depth than DAC-100 headphone amp in terms of hearing further into the music, so that the sound was also slightly more transparent and more open using the HAP-100.  Initially, before burn-in the HAP-100 sounded a bit more forward in the midrange and in it's overall presentation.  Over time the aggressive nature of the HAP-100 mellowed, and it was only slightly more forward than DAC-100.  Music reproduction seems just a little more effortless with the HAP-100 now.  While the DAC-100's built-in amp has a similar level of detail, I still think the HAP-100 takes things just a little further, and with a better signal to noise ratio with low impedance headphones to boot.  This is a big part of what allows me to hear deeper into the music.[/size]
 
[size=10pt]With the LCD-2 rev2 or HE-500 I think the midrange is still a little more forward with HAP-100 than DAC-100, but with HD800 the mids are more similar than different despite an audible improvement in midrange presence.  This is good news, since the HAP-100 retains the great synergy with HD800 that the DAC-100 has.[/size]

 

[size=10pt]Which brings me to my last finding[/size][size=10pt] - the HAP-100 has a blacker background than DAC-100.  When used with very sensitive low-impedance IEMs or headphones, there is a much lower background noise level than with the DAC-100.  With my JH Audio custom in ear monitors (or very sensitive low-impedance headphones) I don't hear any appreciable hiss from the HAP-100 until the volume control gets close to or above 75 out of 99 (music paused, using DAC-100 as source), and even then it's only with very sensitive IEM or very low impedance full size phones near the top of the volume control.[/size]

 

[size=10pt]That means that with actual music playing at those high volume settings it would become quite loud and uncomfortable with my IEM before hiss was ever an issue.  So basically, with normal listening levels in very dynamic musical performances, a person will not have any noise intruding into the music between songs or during quiet passages.  As the volume rises above 75/99 towards the max volume of 99/99, the HAP-100's background noise goes up but it's never higher than that of the DAC-100's headphone amp with it's volume all the way down.  [/size]

 

[size=10pt]In contrast, the DAC-100's audible background noise level with IEM is audible at zero volume but does NOT increase with the volume knob being taken from zero to max (while the music is paused).  This is what makes the HAP-100 a much better choice with IEM and sensitive headphones.  So, in this DAC/AMP combination I found that it's best to set the source to max output and then control the listening volume with the HAP-100 (mostly when using it with very sensitive low impedance IEM or headphones), so most listening is done with the volume below 80/99.[/size]

 

[size=10pt]SUMMARY[/size][size=10pt] - what I love about this DAC/AMP combo is that it gives me 4 digital inputs and 4 analog inputs between the two units, and they can drive a wide variety of headphones and IEM between the two amp sections.  The only feature I'm missing from the DAC is a balanced XLR output to feed my balanced electrostatic headphone amp, so I sometimes use a single ended HEV70 amp in the bedroom rig with loop out to another amp.  So far I still believe that both Nuforce headphone amp sections are best with HD800, and I can't think of another headphone amp near this price range that can match the HAP-100 for listening with the HD800.  [/size][size=10pt]Sure, you can get a cheaper budget amp that is pleasant to use with HD800, like the EF2A, but it can't match the detail, depth, transparency, and refinement of the HAP-100.  [/size]
 
[size=10pt]Upgrading that EF2A to a more expensive EF5 amp is actually less enjoyable with HD800, as would be a $1200 maxed Woo WA6 with the wrong tubes (my warmer WA6 tubes also compress the soundstage).  [/size][size=10pt]The $800 DACmini is not bad with HD800, but over long listening sessions the sound can start to become a little fatiguing.  From memory I would say the similarly priced Grahm Slee Solo II (summer 2009) was still slightly below the DACmini with HD800.  The HD800 are just that demanding for synergy, and a Locus-Design or Black Dragon headphone cable only helps a little (source and amp more important).  [/size]
 
[size=10pt]So while DAC-100 was better with HD800 than LCD-2 or HE-500, in contrast I thought the DACmini was better with my LCD-2 rev1 or HE-500 than the HD800.  But adding [/size][size=10pt]the HAP-100 into the mix seems to bridge that HD800/orthodynamic gap, especially since I just got the LCD-2 Rev2 which seem to be more balanced sounding and easier to drive.  I'd say that the HAP-100 offers me an amp that's good with HD800 and power hungry orthodynamics alike (also it still leads with HD800).  [/size][size=x-small]With my very sensitive Westone ES5, JH Audio 16Pro custom IEM, V-MODA M-100, and Sony MDR-V6 I think that the HAP-100 and DACmini perform on a similar level, as both of these amps have a headphone output that's a bit quieter with sensitive headphones than the DAC-100.  The main difference is that the HAP-100 is slightly more refined and slightly less forward sounding with these phones than the DACmini, while still being slightly more forward than the DAC-100 which was a little more laid back [/size]sounding (maybe too laid back for LCD-2 rev1)[size=x-small].[/size]
 

 

[size=10pt]It's pretty clear that the DAC-100 is still a good bang for the buck for the HD800 owner, who could use it as their sole piece of gear with the addition of a digital transport (CD, computer, digital dock).  But [/size]for those who already have a good DAC or have several analog sources, [size=10pt]the HAP-100 is a better way to get that same HD800 synergy in a decent mid-price amp, while also working better with more sensitive or more difficult to drive headphones and IEM.  [/size]

 

[size=10pt]The HAP-100 sounds pretty neutral and colorations are kept to a minimum, although I sometimes find myself wishing for just a little more warmth and euphonic tube-like sound, but I'd say the same thing about my DACmini at times.  When that happens I find myself reaching for my Nuforce CDP-8[/size] CD player [size=10pt]and feeding the analog outputs directly into the HAP-100.  I suspect that using my Stello DA100 Signature DAC or HiFiMan HM-801 would have a similar effect in adjusting the tone, but I prefer the CDP-8 for it's greater depth, detail, and transparency.  The CDP-8 is a great match with the HAP-100 if one listens to $10 Amazon Prime CDs as much as I still do, and I rate the musicality and quality of sound as top notch. [/size]
 
[size=10pt]In general, the HAP-100 is a very nice and affordable solid state "jack of all trades" headphone amp, which serves as an upgrade to the amp built into the matching DAC-100, but also pairs very well with other sources with RCA outputs.  The fact that it can compete so well with my $1000+ maxed Woo WA6 or $800 DACmini is icing on the cake.  It doesn't remove my need for my HiFiMan EF6 and Eddie Current ZDT amps in my big basement rig, but it does make it much easier for me to enjoy my music upstairs more often, especially with my HD800 at 1/4 - 1/2 the cost of my better amps. [/size]

 
I have to say the JH16Pro Freq-phase are outstanding.  < That's the short version for those who would post TLNR (too long : did not read).  Take advantage of the 15% off pre-Xmas sale NOW!
 
Associated Gear:  My impressions are with my iPad 3 using lossless music and Pico Slim with TWag LOD, as well as with CCK and Pico DAC, and also right from the headphone jack of the iPad 3, iPad mini, and iPhone 5.
 
Photos:  To follow soon, as I am having artwork added to them now.
 
Music Used:  To follow soon, as the list is quite long.
 
Build and Fit:  I originally wanted them in clear acrylic like my first JH13Pro, and think I mentioned that they could add an inconspicuous logo if they wanted to - so I got the Freq-phase logo in thin black lines which is hard to see.  The right monitor is slightly looser than the left, but it's almost impossible to break the seal with extreme facial contortions.   The only time the right seal breaks is when I yawn, and when I'm done yawning it automagically seals again without touching them (sucking sound and all).  
 
My only other issue was that sometimes it felt like the left side was very slightly louder than the right, unless I'd press the right monitor in about 1mm.  At first I was worried that the volume was different due to the looser fit on the right, but then after trying a few more IEM I realize that over time I have developed very slightly more hearing loss and tinnitus on the right than the left.  Sucks to be me (at 50 years old).  The more I worked with the placement and position, I was able to get proper channel balance vs my other IEM, especially when I wrapped some Saran-wrap around the ear-piece stem on the right.  JHA is adding two coats to the right ear-piece now that my review is done.
 
Efficiency is good, and I usually have the iPad volume set between 30-50%, and never more than 60%.  I once tried pushing the iPad well past 70% volume and the sound gets bright and harsh, in addition to being too loud, although the bass doesn't falter.  Switching to the Pico Slim showed much better high-volume performance than what the un-amped iPad can offer, which is not unexpected, as well as producing higher volumes than a sane person can stand.  Regardless, the un-amped iPad can deliver higher clean sounding volume levels with these than I would normally listen, and the iPad amp only starts to fade at levels higher than I would actually use.  Despite the efficiency, they still have less hiss than my ES3X with noisy desktop amps (i.e. ALO Amphora, Nuforce DAC-100).
 
Performance:  Performance is nothing short of outstanding.  I can't think of anything I would change in these.  Sure, if I hear something better in the future I'll know it, but my wish list is empty right now.
 
BASS - In comparison to my old JH13Pro from 2009 which came out on top in my "Three Flagship Custom IEM Review", these have better mid-bass impact and presence.  And they do a better job of connecting the deep bass hump to the mid and upper-bass, without bleeding into the midrange.  And in no way is the bass overdone.  The JH16Pro FP have a bass that's deep, fast, powerful, impactful, and blends perfectly into the mid-bass and upper-bass.  It completely avoids the excessive mid-bass hump of the UE11Pro, and seems to offer the mid-bass impact of the ES5 + the deep bass extension of the JH13Pro.
 
With my JH13Pro I would sometimes feel like I had a subwoofer in the room that was crossed over too low, with a small gap in the mid or upper bass as the sound transitioned into the midrange.  The old JH13Pro have a big deep-bass thump but not quite as much punch higher up.  It was like a slight disconnect was there - the acoustic string bass thump often came from everywhere but not always in relation to the more directional sound of the string pluck, fret slap, and scratch of the fingers on strings.  Not so with the JH16Pro FP.  It's all perfectly connected and seamless.
 
Midrange - The JH16Pro FP's midrange is also more present and lively than the JH13Pro, while the JH13Pro's mids are really sweet but sometimes a little distant.  One reason I was preferring my ES5 lately over the JH13Pro was their improved mid-bass impact but also their warmer, richer, and fuller mids.  The ES5 mids felt more vivid but not as forward as the ES3X, and were warmer sounding than ES3X to boot. The JH16Pro FP give me all that and more.  They seem a little more transparent and not quite as forward as even the ES5, although improved in presence over the JH13Pro.  Goldilocks would say this is just right.  And the very small or mild upper mids peak in the ES5 is not present with the JH16Pro FP, making them more transparent than ES5 as well.  
 
Treble - The highs are smooth and refined, but with exceptional detail and sparkle, yet not rounded at the edges of the attacks despite their silky smoothness.  They're probably a little smoother than my ES5, which are excellent with good material and sources but can sometimes be a little irritating or brutal with some bad recordings, although the ES5 are still an improvement over the ES3X in that regard.  Both Westone IEM are brutally revealing with bad recordings, while the JH13Pro and JH16Pro are a little more forgiving while giving up nothing.  You can still tell if the recording is poor, but it doesn't get on your nerves as easily.
 
Imaging and soundstage is good for an IEM, and I really can't ever pinpoint the sound as coming from tiny little speakers in my ear canal.  Everything sounds coherent, and as if it's coming from sources both inside and outside of my head, with their own point source of origin.  With IEM I never get as much outside of the head imaging as I do with the HD800, SR-009 and HE-60, but almost all of my custom IEM are superior in this respect to my universal IEM.  It's too early to definitively say how this compares to my ES5 and JH13Pro or the others, but at the moment I'd say the out of head imaging is the best of my custom IEM.
 
Summary - The JH13Pro, ES5 and JH16Pro FP are not terribly far apart in performance and enjoyment (at least with my sets), but they are distinctly different in some areas.  So far I give the nod to the JH16Pro for their accuracy, transparency and balance.  I enjoy all three IEM a great bit, and I still prefer the ES5 + older JH13Pro over the ES3X and UE11Pro (as I did in my 2009 three flagship customs review).  But, if I had to pick just one the JH16Pro FP would be it - but It may not be the same for you.
 
My ES3X and UE11Pro are still quite nice, but they are not at the same level of performance as the above IEM, and they really don't see much use anymore.  The ES3X and UE11Pro still make a nice set of backup monitors for me, but when one is spending this much money on custom IEM it just makes sense to go for one of the 2-3 top-tier customs.  I've heard demo sets of UE18Pro and UERM at RMAF, as well as some 1964 Ears and Unique Melody demos, but I don't know how the full custom would sound and nothing in the demo reached out and grabbed me saying, BUY ME.  When I compared the JH13Pro Freq-phase demo to the JH16Pro Freq-phase demos at RMAF, I could still hear the basic sound signature differences between the 13 and 16 that says buy the 16's.
 

V-MODA CROSSFADE M-100 REVIEW.
 
Associated Gear:  Macbook Retina Pro, iTunes 10.7 with Amarra Music Player, CEntrance DACmini and DACport, Nuforce DAC-100, Woo WA6, Eddie Current ZDT, HiFIMan EF5, HM-801, iPhone 5, iPod Nano (5th and 6th Gen), CablePro Reverie LOD, Whiplash Audio TWag V2 LOD, Headamp Pico Slim, and RSA SR-71b.
 
MUSIC USED:  See review.
 
M-100 FEATURES (from website):
 
- Modern Audiophile Sound
50mm Dual-Diaphragm drivers (patent pending)
Analog Noise Isolation
No Batteries or Artificial Processing
3+ Years of Ergonomic R&D
Balanced, layered, clean yet Deep Bass, Vivid Mids and Ultra-Extended Highs
Maximal 3D Soundstage & Minimal Leakage
Tuned V-PORT
 
- Military-Level Materials & Quality 
MIL-STD-810G Test Standards
Virtually Indestructible CLIQFOLD Headband
6 band frequency response Quality Control
Exoskeleton Hard Case
ABCP® - Anything But Circles & Plastic Materials
Detachable Kevlar® reinforced SharePlay and Universal SpeakEasy Mic cables
1/4" adapter included
 
PHOTOS:  [review edited to fix a missing photo]
 

 

 

 
 

 

 

 
 

 

ACCESSORIES:  
 
The M-100 comes with a nice hardshell zipper case, 1/4" adapter for the 1/8" plug, and two 1/8" (3.5mm) plug headphone cables - one with a mic and button, and the other with a short splitter and extra 3.5mm jack to allow plugging in another set of headphones.  The other end of the cable that plugs into the headphones is terminated in a 1/8" plug as well.  The two headphone cables are covered in a tight weave fabric, which feels more upscale than the cheap rubbery cable with my HD25-1 II or Shure SRH-840.  I tried the splitter cable at RMAF, and with a second M-100 connected there was no change in sound quality when connected to a DJ Mixer board and amp.  If the cups could swivel forward to uncover one ear this might work better as a DJ headphone, although the extra hinge it might weaken the super-strong headband.  At RMAF Val told me that we could daisy chain 4-5 M-100 together without causing problems.
 
With the single button on the headphone cable I was able to pause the music (1 click), or skip forward (2 click) and back (3 click).  The button also works with Siri on my iPhone 5 if I press and hold it, which is wonderful.  The microphone pod in the cable is closer to the ear cups and mouth, while the button pod is at an easier to reach location at mid chest level.  The plug is also small enough to be used with just about any iPhone case out there, even those with with a small headphone jack hole like my Speck candyshell case.
 
INITIAL IMPRESSIONS:
 
I spent a bit of time with the V-MODA M-100 at Rocky Mountain Audio Fest 2012 (RMAF), and posted some early impressions about them in the RMAF 2012 impressions forum at Head-fi.org that night.  I was excited about these and was ready to buy a pair of matt-black at the show, but they only had a few samples remaining until December, so they couldn't sell me a pair until then.  After two days of pleading my case I was able to get a loaner pair to review.  To last me until December I also got a pair of M-80, which I hope to review later and hand down to my daughter or son.  
 
Now that I've had these Shadow Black M-100 in hand for a few days, the shiny black shell surrounding the matt black ear cup's center panels has grown on me.  At first I liked the all matte black ones better, but I thought the headband on these Shadow black phones was more attractive. I love the look of the suede headband that comes with the Shadow.  These are stylish without feeling gaudy.  I would not be embarrassed to wear them out in public, or in front of my kids.
 
I was initially drawn to the V-MODA M-100 not by the looks but by necessity.  Before RMAF I had misplaced my Sennheiser HD25-1 II and I wanted something better to replace them as an inexpensive closed headphone with good isolation.  My SRH-840 are a little too big to be portable, and didn't isolate as well the HD25-1 II.  After the demo at RMAF I felt these could be a good replacement for the HD25-1 II.  I was sad that I wouldn't be able to compare them for more than the 10 minutes I had with someone elses HD25-1 at RMAF.  
 
As luck would have it, when I got home from Rocky Mountain Audio Fest my son pointed me right to the missing headphones, hiding in a black Sennheiser case on my dresser.  For some reason someone had put them away for me and didn't tell me. This meant that I'd still have a good isolating phone if I didn't buy the M-100, which I felt would make me less biased.  But if I hadn't thought I'd lost the HD25-1 II before CanJam @ RMAF I might have glossed over the M-100 and any other closed headphones altogether.  That would have meant no review.  Needless to say, after doing comparisons with my HD25-1 II, SRH-840, and ATH-A900 at home I'm still convinced that I need the M-100.
 
In a nutshell, the M-100 is a fuller and richer sounding headphone than my HD25-1 II, with stronger bass and less grainy treble.  The M-100 is actually more laid back and less aggressive sounding than the HD25-1 II, which I sometimes think sound too much like lower or middle of the line Grado headphone.  That's not such a bad thing, but it limits the HD25-1 II as far as what I can enjoy with them.  This especially in light of the Sennheiser's flat soundstage which presents more of a wall of sound, as well as limits the immersion in the musical experience with many genre like classical music and live jazz recordings.  
 
I tended to think of the HD25-1 II as my "rock music" headphones with isolation, and even then I would prefer a bit more bass impact from them.  The M-100 give me that and more, while throwing out a bigger and more transparent soundstage that is unusual for a mid-priced closed headphone like this.  And the icing on the cake is the M-100 are more comfortable to wear for long periods than my HD25-1 II which sit on and compress my ears.
 
In comparison to my Shure SRH-840, the M-100 mids are fuller and not recessed in the lower mids like the Shure seem to be.  And the M-100's stronger bass lends a bit more weight to instruments and the illusion that they are in the room with me.  The M-100 soundstage is also a bit bigger than the SRH-840.  The SRH-840 and HD25-1 II are a little brighter in the treble region, which does make picking out small details in the music a little easier if these are all paired with a high output impedance amplifier. I have a comfort issue with the SRH-840 in that the cups are shallow and my ears hit the baffles, but not so with the M-100.
 
My ATH-A900 have been recabled and internally dampened, and sounded a lot more like a Denon D2000 the last I did comparisons.  The problem is that means the same V-shaped frequency response with recessed mids in relation to the bass and treble, and the treble still isn't all that smooth.  All of my comparison phones were a little brighter than the M-100.  With good gear and good quality masterings I wouldn't say the M-100 are too dark, and although they are darker than the HD25-1, SRH-840 or ATH-A900 the M-100 treble seems a little more refined to me.  The ATH-A900 are extremely comfortable, but often too loose and don't retain their position on my head when I recline my chair.  They also don't isolate much at all compared to the M-100 or HD25-1 or SRH-840.
 
SYNERGY:
 
The first time I tried the M-100 at RMAF was with my iPhone 5 and 5th Gen iPod Nano and a CD ripped in Apple lossless format. I listened to Amanda Palmer (AFP) playing Radiohead songs with her ukelele; and in "Fake PLastic Trees" I thought the ukelele was clearly coming from outside of the headphones.  When Amanda started singing after the intro, her voice was full and inviting without any overdone lower mids or missing ambience and air.  And the music's weight, body and presence was great.  
 
I then listened to the M-100 with a $2700 April Music Eximus DAC/amp at the Moon Audio table and fell in love even more (with both the M-100 and Eximus).  My 5th Gen iPod Nano paired with a CablePro Reverie line-out dock and Pico Slim amplifier fell between the iPhone and Eximus in sound quality, with a surprising level of detail for such a small audio rig.  All of these with a lower output impedance than my Nuforce DAC-100 and CEntrance DACmini that I used once I got these headphones home.  What I heard at RMAF sold me on these phones, as they did other head-fi member like jude and Asr.
 
At home, with some amps that have an output impedance of around 10-15 Ohm the M-100 did develop a little more bass-boost than is optimal, but that's not the M-100's fault but rather an impedance mismatch to blame. Fortunately it's not an issue with every music track played through these amps, and one song or album might be okay while another was just a little troublesome.  But if it was an issue it's improved greatly just by using the EQ in iTunes or Amarra Music Player to take out about 2-3 dB at 125Hz and 250Hz. It was never bad enough that I felt I must use EQ with these amps.
 
Regardless, with my Pico Slim and SR-71b portable amps, Woo WA6, HiFiMan EF5 or Eddie Current ZDT desktop headphone amps, the output impedance is low enough to not be an issue.  The M-100 also play very well with my HM-801, iPhone 4S, iPhone 5, and iPod Nanos (5G and 6G) right out of the headphone jack. So, if I note elsewhere in my review any issues with bass bloom or slightly decreased bass control, know that I was using the high output impedance amps at the time.
 
Clearly, changing to an iPhone/iPod or an amplifier with low output impedance the week after I started my review negated the need for the small amount of EQ that I tried in parts of the review.  However, I didn't want to re-write all of my review that was almost completed without using the amps in question, because it's important that people see what the synergy with different gear is like.  While many of my high-end headphones don't mind the slightly elevated output impedance (LA7000, HF-2, HE-500, HE-5 LE, LCD-2 r1, HD600, HD800), I think that proper impedance matching is a little more important with the M-100.  With that sorted out they did very well with all the program material and no EQ required.
 
IMPRESSIONS - mostly with DACmini (10 ohm) and DAC-100 (15 ohm), and other home amps:  
 
The day after I returned from the Rocky Mountain Audio Fest I started listening to the M-100 with several of my home audio rigs.  The DACmini and DAC-100 are the ones I usually have hooked up to my Macbook Pro, and the most convenient.  One thing I noticed was that the M-100 were very sensitive and efficient, and revealed the zero volume background hiss of the DAC-100's headphone amp, which previously I had only heard with IEM or earphones.  I didn't hear any hiss or noise with my other amps, including my HiFIMan EF5 which is also too noisy to use with IEM.
 
Up first was Lori Bell-Ron Satterfield Duo on the Nuforce Bluport Jazz Sampler in 24/96 via my Nuforce DAC-100.  In direct comparison the M-100 has a better soundstage in every dimension than my HD25-1 II which have a fairly flat or shallow soundstage front to back in comparison.  The M-100 is fairly transparent despite the strong bass, but there was a small amount of mid-bass bleed of the string bass and acoustic guitar into the lower mids, due to the amp's >15 ohm output impedance.  But then the flute was so "right there in the freaking room with me" that I almost turned my head to look for it!  
 
This portrayal of a spacious soundstage was reinforced when I played Tabula Rasa "Part: Fratres" with Gidon Kremer and Keith Jarrett.  I could place the violins and piano easily in the concert hall, with an enveloping sense of space that was surprising for a closed phone in this price range.  Many of my classical recordings that were done with wide spaced and somewhat distant mics usually lose a bit of bass impact and presence from the instruments being unamplified in a large hall.  However, the M-100 retained the weight and warmth that I've heard before in live performances when the bass strings, brass, and tympani come in full strength (such as in my 24/96 recordings of Elgar Enigma Varation No.9 • Lawrence Foster • Houston Sym. Orch.• Recorded Live, and Tchaikovsky: Hopak from Mazeppa • The Minnesota Ochestra, and especially in Jeu de cartes • Charles Munch • Boston Symphony Orchestra).
 
With female vocals in Chesky's "Audiophile Voices I & II" the M-100 sound full bodied, and with the DAC-100 and DACmini there was only small amount of bass bleed into the lower mids, but not too bad or distracting, especially if you've been to enough concerts to be used to hearing close mic'd and amped vocals that you forget about it.  In other music selections on the Nuforce Bluport Jazz Sampler album, with piano's I thought the M-100 lacked some of the super fast transient response that I get with high end phones like the HiFIMan HE-500, Audeze LCD-2 and Sennheiser HD800.  However, their speed and performance with pianos improved noticeably when I selected other piano recordings such as Keith Jarret "The Koln Concert" in 24/96 or Maxense Cyrin "Novo Piano".  The transient response improved even further when used with a low output impedance amp like the Woo WA6, proving that synergy and recording quality are both just as important.
 
I'll note that pianos are usually hard to reproduce with the stunning clarity of live instruments, but these can do a pretty respectable job with good music selections, even with my DAC-100 and DACmini.  I pulled out the venerable Jazz at the Pawnshop.  In the song "Lady Be Good" for example, I was pleased with the piano presentation offering pretty good transparency and no bleed-over.  When the saxophone kicked in at 2m 10s it felt just a little more forward and up front in respect to the rest of the band than I am used to.  More like he was playing right up to the microphone at the edge of the stage.  I went into the iTunes EQ and pulled back the 125Hz slider by about 2dB and the 250Hz slider by 2.5 dB which took care of the bass bleed into the saxophone.  Despite the M-100's laid back nature and treble, the high hat cymbals and ride cymbals that are struck in the background behind the piano for the first minute or two were clean and sharp.  And you could still hear them shimmer in the background through the entire song, although slightly recessed in volume.  
 
At the other end of the spectrum, when switching to the Batman Begins soundtrack, you can feel all the weight and power you'd expect from a 5.1 sound system with subwoofer in your home theater.  Sometimes I'll skip right to the song "Molossus" for a demo, but the sound was so immersive and surrounding when I started track one that I found myself listening to the entire album while typing this, even though I was supposed to be spending that hour with a wider variety of music.  Likewise, I greatly enjoyed the M-100 with many other orchestral movie soundtracks from Hans Zimmer and others, such as Gladiator, Pirates of the Carribean, The Dark Knight, Lord of the Rings, etc. This needed no EQ with my high or low impedance amps.
 
These headphones give a very powerful presentation, with huge weight and depth and immersion into the movie soundtrack.  By blocking the outside noise, one doesn't need to crank up the volume to higher than safe levels either.  But just like being addicted to the acceleration of a fast car, it's sometimes still fun to turn it up the volume and feel the power and weight these portray.  I did so and was not disappointed.  They can play at extreme volumes and not complain one bit. The M-100 is the first efficient headphone with which I have maxed the volume on my DACmini, and it did so without distortion at incredibly high and dangerous volumes.
 
And with music like Pink Floyd "The Wall" or Black Eyed Peas the M-100 found their element as well.  With "The Wall" and the DACmini I preferred to use some light bass-reduction EQ the music as above, but switching to the iPhone 5 or a low impedance amp with "The Wall" required no EQ.  With Blackeyed Peas I preferred the M-100 without any EQ, regardless of amp.  In one test I cranked up "Boom Boom Pow" and "Imma Be" on the DACmini to such high volumes that I actually felt my ears bouncing and saw my vision blur, surely exceeding 120 dB without clipping.  After that I tried some V-MODA Faders VIP plugs to reduce the volume level for hearing protection during high volume tests, and I could hear clean music without clipping at very high volumes (I learned the earplug trick when I used to do car stereo competition in college - turn it up until it was just below clipping and then look at the dB meter).  
 
With the same desktop rig I switched to The Dark Night soundtrack, and in "Why So Serious" the sucking throbbing low 20Hz bass notes really felt like I had a plunger hooked up to my ear canals with somebody working it like a butter churn.  Seriously, I don't recall the last time I felt such power and impact from a headphone without clipping, except maybe when I got my first Koss Pro 4AAA when I was a teenager, played via Marantz 2240 receiver.  With the Bella Sonus album, in the intro to "Enamoured" it throws out a few 20Hz notes that can be clearly heard, while the low notes often disappear with other mid-priced headphones.
 
To see just how low these go and how they play from 20Hz - 20Khz, I tried out Michael Knowles "Binks Audio Test CD" where bass is strong to 20Hz and can still be felt at 16Hz. There is a small hump around 160-250 Hz as well as a small audible dip in the frequency response from 2150-5000 Hz, but no spiky treble peaks and especially nothing noted in the 6KHz range that would lead to any sibilance.  My 50 year old ears roll off after 12,500 Hz and I can clearly hear the M-100 at that point, but with the volume turned up to compensate for my age the 16Khz tone is also definitely audible with these. 
 
As I said before, some recordings sound a little "bloomy" with high output impedance amps, like "The Wall", but with other recordings the bass and overall clarity is just fine without EQ on those amps.  Switching to the Nuforce DAC-100 to play Jimmy Cobb Quartet "Jazz in the Key of Blue" in 24/96 was one example of such.  It was very detailed and well balanced with the M-100, without being dark or boomy.  This was another time that I found myself listening to the entire album when I was supposed to be listening to everything I could throw at the M-100.  I didn't realize I had become totally immersed until the next album in iTunes started playing, which was Keith Jarrett "The Koln Concert" in 24/96.  And with this recording the M-100 did a fine job of reproducing the delicate piano notes that seemed to hang in the air, with great ambience and space of the live hall where it was performed.
 
Next I pulled up Sara K "Hobo" in 24/96.  This album also showed off the clarity and PRAT that the M-100 are capable of, albeit with continued strong bass emphasis.  I also tried the 24/96 Chesky Records "Explorations in Space and Time", which proved that the M-100 can transparently recreate a large hall with ambience and air, and still hit super hard with the drum impacts.  In contrast, with the same amp I listened to "Fever" on the Ray Charles "Genius Loves Company" in 24/96 and thought the bass sounded a little boomy, requiring that previous EQ of about minus 2-3 dB at 125 & 250Hz.  This went on and on where many albums were just fine with the 10-15 ohm output impedance, and if not it was fixed by a low impedance amp or a small amount of EQ in the bass.  
 
PORTABLE IMPRESSIONS:
 
Even better news is that for the intended playback devices like iPhones and other iDevices or portable gear, with or without a portable amp, the synergy is very good.  This makes a great portable circumaural headphones for iPhone use, with a mic and without need for an amp.  However, it's good enough to reveal the differences between sources, so choose well.  
 
I don't think the iPhone 5 sounds as good as those that came before it, and I preferred my 5th Gen iPod Nano, iPhone 4 and 4S, and iPad 3 over the iPhone 5. The iPhone 5 is reported to have a slightly higher output impedance than the 4S and older iPods, but it still worked well when using it with the M-100.  Unfortunately the clarity, spaciousness, and detail still can't compare to the DAC-100 or DACmini (or even the iPhone 4S).  Note, the iPhone 5 needed a lot of burn-in to open up, and it wasn't fully burned-in by RMAF.  After almost 2 months it sounds much more open, and is more pleasing to listen to than a month ago when I started working on this review.  The iPhone 4S, 5G Nano and iPad 3 still hold an edge over it, but I can still enjoy them with the iPhone 5 despite it's slight veil over the other iDevices.
 
I really appreciated that I don't need to use an amplifier to drive the M-100 well, because with an amp piggybacked to the iPhone you can't use the mic or the controller button on the cable.  The other reason to avoid an amp is that the iPhone 5 now lacks a line out to connect a line-out dock to an amp.  The cheap Apple Lightning to 30-pin adapter plus a line out dock and Pico Slim sounded pretty dull, bland and lifeless vs the headphone out, so I did most of the listening via headphone out.  
 
For a comparison of power output from the iPhone I played Mercan Dede "800" in lossless via the DAC-100 at 50% volume, and really got into the thumping rhythm and drums.  I then switched to the iPhone 5 headphone out with the same album, and the M-100 right out of the headphone jack only needed to be set at about 65% volume to match the volume of the DAC-100 at 50%.  
 
Setting the iPhone 5 volume at 50-80% is all you will ever need with most music.  Above 80-90% it was louder than I normally listen (without distortion I should add).  And 100% was uncomfortable after 15-30 seconds but still sounded clear with most music.  Dropping back to 65% on the iPhone was just right for me after that.  This is loud enough to drown out most traffic driving by, without blocking the sound of a honking horn or screeching tires.
 
SUMMARY:  
 
With a wide variety of high-end, mid-fi, and lower budget rigs the M-100 never failed to please.  They have a solid high standing in the ranks of fun and easy to drive headphones that can also please audiophiles, although I might not place these in the ranks of audiophile headphones, mostly due to their emphasis on the low end and their laid back treble.  Still, I thought their timbre and tone reminded me most of being like a "closed Sennheiser HD650", although with a little extra bass and slightly less detail.  That's a good baseline sound signature that can appeal to most people.
 
Compared to other popular passively isolating headphones near this price range, such as Shure SRH-840, Sennheiser HD25-1 II and Amperior, and Beyer DT-1350 or Custom One, I really prefer the M-100 (my ATH-A900 and Denon D2000 don't really offer much if any isolation).  While the HD25-1, ATH-A900 and SRH-840 that I have here at home have a more present treble that makes them sound crisper (and maybe seem more detailed at times), those lack either the weight, body, presence, or depth of stage that brings the music to life and makes you feel like you are there.  The only other closed headphones that I think could compete with the M-100 in this category, that I heard at RMAF but don't have on hand to compare, were the Sennheiser Momentum and Sony MDR-1.
 
And, the M-100 don't have a problem with presenting details if you have the gear and the ears to hear it.  For those who are getting older and experiencing high frequency roll-off, or using these with too high of an output impedance, then the M-100 might start to sound a little too dark.  But even then, it was easy to enjoy them with just a touch of EQ, although I didn't find myself touching the treble with the EQ.  
 
Personally, I found it easier to just listen to them as they are without adding or removing anything with EQ.  If I MUST EQ a headphone to enjoy it, like with my last two pairs of Darth Beyers, then they aren't worth owning.  The M-100 on the other hand are a keeper.  Now, if I can only keep my son from sneaking in and borrowing them from me.

HM-602 IMPRESSIONS:  
 
At RMAF 2010 last weekend I picked up a demo HM602 which had been burned in by Fang, and I've put an additional 24 hours on it since Saturday night.  Low volume channel balance with the HM 602 is good with sensitive IEM, whether in low or high gain, just like the HM 801 which has enough power for HD800 and yet works great with IEM (and has no gain switch).  I have not unpacked my full size phones from RMAF yet, and all my listening was with my best custom IEMs.  I typically do not listen to full size phones with a DAP anyway.
 
GEAR:  I did most of my listening with my Westone ES5 custom IEM because they are my best IEM and they can be ruthlessly revealing - I don't miss a thing with them.  My JH13Pro have very good detail too, but with a little bit of added low-bass boost, so I tried these IEM at the end as well to look at synergy with all the players involved.  
 
I initially began by comparing the 602 with my 16Gb 5G Nano (headphone out).  While they are both a 16Gb DAP, the 602 can be expanded through the SD card slot and the Nano is stuck at 16Gb.  The Nano has the advantage of syncing with iTunes, but it can't play 24 bit music like the 602 nor can it function as a USB DAC.  I later included the HM 801 which is an upgrade to the 602, and the iPhone 4 which is an upgrade to the 5G Nano.  I've always felt the iPhone 3GS/4 were my best sounding iPods, just below my previous 5.5G iMod.  But in previous comparisons I felt the 801 beat my iMod as a source, and the built-in amp was very close to my best portable amps.  So for the most part I left my amps out of this comparison because my biggest goal was deciding which was the best DAP for portable use, without needing to carry around extra cables and amps.  I did do a brief comparison using the Pico Slim because it's my most portable amp, best with my ES5, and closest in timbre and tone to the 801's headphone amp.
 
MUSIC:  I started with a 24/96 FLAC of Jimmy Cobb Quartet "Jazz in the Key of Blue" and Carla Lother "100 Lovers" in 24/96 on the 602, but a 16/44.1 Apple Lossless conversion of the same albums on the Nano, created with MAX on the Mac.  It seemed fair to listen to them with the best quality music that they can handle, to extract their best performance possible.  I believe the 602 down-samples the 96Khz music to 48Khz, but it does display the music as 24 bit on the display.  After my initial listening impressions, I went back and listened to a 320K MP3 rip of Bella Sonus "Enamoured".  This can be a bright or sibilant recording that would be good to test the players with a compressed format to see how they handle it, and it also has some very deep bass notes that go as low as approximately 25Hz in the beginning of the first song.
 
TREBLE:  What first came to mind in the comparison is that the 16Gb iPod Nano 5G is a little brighter sounding than the 602.  Although neither one seems too bright or too dark to me, the Nano seems slightly crisper but not actually more detailed or speedy.  Without the forward or slightly aggressive highs of the Nano, the 602 still has a nice sparkle and shimmer in the cymbals, while the 5G Nano has a slightly harsh bite with the trumpets (although not sibilant or sizzling).  
 
At this point I tried the HM 801 with this same 24/96 music, and I felt that it had slightly more treble presence than the 602, making the 602 sound slightly rounded off or soft in the highs in comparison.  The 801 offers the same smooth refined highs with slightly better treble presence.  The 801 also offers slightly better transparency and clarity than the 602 which I still preferred over the 5G Nano.  
 
While the treble is where the 602 and 801 differ the most it's not a huge difference, with both being more refined and natural than the 5G Nano which is slightly boosted in the highs (but not too bright and better than my previous 4G Nano).  I switched to my iPhone 4 with this same music in 16/44, and I felt the iPhone 4 probably has a similar treble presence to the 5G Nano, but it's more refined sounding and closer to the 801 in that regard.  Throughout my listening I never felt the need for more treble with the 602, but it seems to be maybe 1-2 dB below that of the 801 or iPhone 4.  My 48 year old hearing starts to roll off at 12.5KHz and is fairly well down at 16Khz, and you'd think that I'd prefer something brighter sounding but I don't, and I suspect that my brain has accommodated for this loss over the years.
 
MIDRANGE:  The 602's mids are also a little fuller, warmer, richer and more life-like than the mids of the 5G Nano, making the 5G Nano's mids seem slightly thinner and slightly distant in comparison.  This makes the jazz guitar on the Nano sit a little further in the background than with the 602.  But the Nano also renders trumpets and guitars with less body than the 602.  Overall the soundstage of the 602 seems slightly more forward than the Nano, due to the mids being more natural and solid.  But without having done this comparison I would have never thought to call the 602's mids forward and I'd say they are just right.
 
The micro-detail, air/ambience and space is still very good with the 602, so I don't lose any of the size of the venue due to a more forward sound and rolled off treble, because I can still hear all the room echos intact with good separation.  The listener is moved slightly closer to the stage with the 602, and farther away with the 5G Nano.  The iPhone 4 is not as distant nor as forward sounding, but it's the 602 sound-staging that sounds more correct to me, and it comes very close to the 801 in this area.  The iPhone 4 is very close to the 602 and 801 in the mids, and it's better than the 5G Nano as well, but it's still not quite up to the level of the 602/801.  With iPhone 4 the trumpets and pianos don't carry quite the same weight or presence that they do with the 602/801.  Again, there is not a huge difference but it's noticeable between iPhone 4 and the 602/801.
 
BASS:  I also think the 602's bass is slightly more present or full-bodied sounding than the 5G Nano.  The 602/801 and iPhone 4 are similar in that regard and they give a little better foundation to instruments like drums or string bass, although the 5G Nano is not lacking in bass nor is the 602 bass heavy in comparison.  Typically the bass is one of the things I think the 5G nano does better than its mids or highs.  However, the Nano and 602 headphone out still do not go as deep as when I use an LOD with an amp like the Pico Slim.  Here I found the 5G Nano and the 602 to both be slightly rolled off at 25Hz, and even more so at 20Hz when comparing them to 31Hz and 40Hz tones (Bink Audio Test CD).  The 801 and iPhone 4 were both a little stronger at 20Hz and 25Hz than the Nano or 602, although still not as strong down there as the Slim.  So while the 602 bass is slightly fuller with slightly better impact than the Nano, its extension or depth is about the same.
 
AMPLIFIED:  In a brief comparison, adding the Pico Slim amp to any of these DAPs adds more bass extension, and slightly more channel separation, soundstage, air and space.  The improvement over the iPod's headphone out was bigger than over the 602/801 headphone out which falls closer to the quality of the Pico Slim.  But with the JH13Pro + Slim the bass is boosted a little more than I like for medium to loud volume listening, and I preferred the 602 headphone out with JH13Pro unless listening at lower volumes.  The ES5 sounded great with any of these players, but I have to admit that they were still a little better when using the Slim.  Again, the 801's and 602's line-out (with jumbo cryo silver X mini-mini) served as a better source to feed the Pico Slim than using any of the iPods with TWag LOD.  
 
For un-amplified listening the 801 is my first choice by a small margin, but the 602 is not far behind as my second choice.  Even my old iMod as a source for the Slim didn't have the same sense of space or refinement as the 801, so the iMod is gone now.  I suspect that as close as the 602 is to the 801 that it would be ahead of the iMod as a source as well. In this sense the 602 is a bargain compared to a $500 iMod + $300-500 for LOD and amp.  The money saved could by a lot of 32Gb SD cards for more music, or a nice set of IEM.  I did feel that the Gap between players narrows when using the 602's line-out to the Pico Slim, but the 602 is still a better source. And, I don't feel like I'm missing much at all with using the 602's built-in amp and keeping the package more portable.  I would not give up my iPhone 4 for the 602 because I use it for calls, surfing and email; but the 602 offers a better musical experience while saving the iPhone 4's battery for phone calls, web surfing, movies or games.  
 
USB DAC:  Unlike the iPhone 4, the 602 can be used as a USB DAC/amp to upgrade your computer's built-in sound.  The USB DAC sounds better than the Macbook Pro's built-in output, but it's not as detailed and spacious as my upgraded iBasso D4 or DACport.  In the end I feel that both the 602 and 801 sound better listening to music on the SD card than through USB (although the 801's coax input is quite good too).  Maybe sometime in the future I will do a more in depth review of the 602 as a USB DAC only, but I don't see that as its primary purpose and I wont be using it that way.
 
PROS/CONS:  As far as Pro's and Con's go, the best thing about the 602 is the great sound, followed by not having to tether it to an amp with an LOD and use a rubber band or velcro to hold everything together. Being able to use small wallwart with a standard single tip instead of the double tip charger of the 801 is another bonus, as it makes it much easier to carry a charger when traveling or to find a car charger for it.
 
I see the biggest problem with the 602 being the lack of Apple Lossless file support.  Most of my lossless music is stored as ALAC, and not FLAC, AIFF or WAV.  I do have several 24/96 hi-res downloads that came as FLAC files, and they play great with no modification.  In addition to that, I converted my favorite 25-30 albums from ALAC to FLAC for the 801/602.  But I'm not happy having to convert another 70Gb (approx 250 albums) from ALAC to FLAC and store it for possible use with the 602/801 later. Plus I have another 250 CDs to rip into iTunes and don't want to do both ALAC and FLAC.  However, most of my ALAC music has a second copy stored as a 256-320K MP3 to fit more music into portables with limited memory, and the 602 sounds very good with these lower bit-rate files.  So, I'm not locked out of listening to most of my music library, only from listening to most of my lossless music unless I'm willing to put in the time to convert everything once again.
 
A second con is the 602's size, as it is about as thick as three stacked 5G Nanos, and 1.5x wider - making my 5G Nano + Pico Slim a slightly smaller package.  On the other hand, while the 602 is thicker than my iPhone 4 + Pico Slim, it's not as long nor as wide.  Still, it will never be as portable for front pants pocket carry as a thin un-amped iPod.
 
The SD card expansion is nice, because one can add more music without having to carry around a laptop to sync music onto the device.  I have three 8Gb SD cards filled with music, which can expand the internal 16Gb with music that wouldn't fit otherwise.  The line out using a normal 3.5 mm jack is another plus, because it can be connected to other amps, docks and car connection kits without needing a proprietary dock connector.
 
SUMMARY:  The HM-601 is a respectable portable DAP which provides better performance than the iPods I've tried, and doubles as a USB DAC/amp to upgrade your computer's sound.  It's not cheap, but still in the ball park price of an iPod + LOD + amp and offering as good or better performance for the price.  Its slightly muted treble extension doesn't take away from the experience for me; but some may not like that aspect of the sound, especially with a rolled-off treble or dark sounding earphone.  It has an inviting musical quality which draws me into the performance just a little better than an iPod + amp, although my iPhone + Pico Slim comes close.  And it has better synergy with my JH13Pro than my Pico Slim.
 
--------------------
* I rated value as a 4.5/5, in that while it sounds better than an iPod + amp costing more money, it's not as versatile as a $229 Touch with $220 iBasso D4 amp for the same price which can also surf the web, email, facetime chat, run apps and play games, etc
** Design, Battery life and User Interface are 3.5/5 for being average.
*** Overall 4.5/5 is for portable gear, where the 801 or desktop rigs would score 5/5 - the high sound quality of 4.5 is more important than the 3.5's in other areas and gave it a higher overall score than the sum of the sub-scores.

UM3X Review - starting from scratch.  
 
My rating is among other universal IEM in any price range, but not vs custom IEM.  I consider a 5/5 to be the best that all universal IEM strive to reach, which I may not have heard yet.
 
I've posted in the past that I liked the UM3X almost as much as the W3, where most of my comparisons were done with my UM56 tips which tend to equalize the disparity a bit between these two IEM.  I've compared the UM3X with W3 at Canjam 2009, Colorado meet July 2009, and then my most recently in Oct 2009 at RMAF (after losing my 1st pair of W3 and UM56).  When I compared these two IEM with Complys tips at RMAF, I walked away with another W3.  Since then I had forgotten how good the UM3X sound, but I picked up a pair with the removable cable  last Friday so that I could use them with in balanced mode with my Protector amp.  But before tonight I hadn't even tried them with the Protector or Pico Slim, because I've been enjoying them so much with my Macbook > Nuforce uDAC-2 and plain old iPhone 4 headphone out.  They don't beat out my ES3X or new ES5, but they definitely perform very well for a universal IEM, coming out ahead of my Livewires T1 or Alien Ears C3 customs (and my SE530 in a custom shell).
 

 
One of the first things I noticed was that while they are just as efficient as my W3 or ES3X, they have noticeably less hiss when plugged into my ALO Amphora amp.  With the volume turned down I can hear more hiss with my W3, and my ES3X reveal so much hiss that I stopped using them with the Amphora.  But somehow my UM3X are fairly quiet with the Amphora (and so are my very sensitive Westone ES5).  The hiss with UM3X is below the level of my chronic tinnitus, and not intrusive at all.  With my other quieter amps the UM3X are silent.  I used to recommend the IE8 as a good universal IEM for the Amphora since they didn't hiss with it, but now I can also recommend the UM3X too. 
 
I was quite pleased to find that my UM3X with removable cable came with the complete Westone fit kit, with a wide variety of tips included, and not just the Complys.  I don't know if this comes with all of them, or just the special package that was meant for me.  I've settled on using either my UM56 tips or the single flange silicone tips, but I wasn't getting a good seal with the short Complys that were pre-installed on them.  I typically keep my custom UM56 tips in a carry-case with my W3 because those really benefit the most from custom tips (almost demand them I should say, although long Complys are my second choice with W3).  But I like the single flange silicone on the UM3X more than on the W3, and they're quick to insert into the ears.  So I'm fine with leaving the UM56 paired up with the W3 and just using silicone universal tips with the UM3X.  For the benefit of others who don't have the UM56 custom tips, I will compare the UM3X to the W3 here while using universal tips only, and this makes a difference over which IEM I prefer.
 
The UM3X frequency response is definitely more neutral than the W3, and I was afraid that they would start to sound boring after a while, but I've listened to them many times since I received them and they haven't disappointed me yet.  With the single flange silicone tips the UM3X seem to sound best with a shallow insertion, while the W3 sound best with a deep ear canal insertion.  So, switching to the W3 with the single flange tips pushed in deeply, I find the bass to be similar in depth and power, but the W3 are somewhat boosted in the mid-bass vs the UM3X.  The mids of the W3 are not as forward as the UM3X, but not terribly recessed either.  The UM3X highs are slightly muted vs the W3, but not dark in any way, and not as aggressive as the W3 can be with the wrong tips or wrong insertion depth.  The UM3X have better treble sparkle than the IE8 that I got rid of at RMAF, which seemed to have a recessed treble in comparison.  
 
Overall, I would say the UM3X have just the right amount of bass, mids and treble to strike a nice natural balance, while the W3 have more of a "fun" frequency response if using the stock tips (but more natural with UM56 tips).   I also tried low bit-rate downloads with the UM3X (Breaking Benjamin, Dave Matthews), and the UM3X seems a bit more forgiving of low bit-rate downloads than the W3.  This also varies somewhat according to what amp I am using, and the Amphora was best with UM3X, closely followed by the Pico Sim and uDAC-2, then DACport, iBasso D4, iPhone 4 headphone out, with the Protector last but still in the running.  With high quality recordings in lossless, the amps grouped more closely together in performance.
 
Tonight I started by listening to Eiji Oue Minnesota Orchestra "Rachmaninoff Symphonic Dances" via Macbook Pro > uDAC-2 and the UM3X sounded very immersive and detailed, smooth and musical without any etch, with nice deep bass and ambience that gives the venue good space and size.  The presentation is more like being in the 1st or 2nd row than 10th row like the W3 ("mid-hall" if the W3 are using the single flange tips with shallow insertion).  But they're not so forward as to place you right on the stage.  And the depth changes depending on the recording, so I think that maybe they do reflect fairly well what the producer had in mind.  This particular recording is very dynamic, and in the louder parts I kept thinking "this is gonna disturb my wife, I better turn it down", and then I'd remember that I'm listening to an IEM.  So, I'd have to say these are pretty transparent sounding!  These are noticeably more transparent than the Monster Turbine Pro Copper that I had here on loan last week, or my Triple.fi 10 Pro (TF10Pro).  
 
Changing to Eva Cassidy "Live at Blues Alley" with the W3 still in my ears, I can hear their mid-bass boost more easily.  However, the vocals are rich and present, and not recessed as some have claimed (unless I pull the W3 out so they are inserted less deeply).  Switching to the UM3X with this same music I find the mid-bass to be a little more tame and controlled, i.e. better balanced.  Although the UM3X have slightly less impact and power in the mid-bass, they go down just as deeply.  This bass levels are at least on par with other IEM like the TF10Pro, but without the colored mid-bass of the TF10Pro.  (note - the W3 bass is closer to the UE11Pro.)  While more forward sounding than the W3, the UM3X mids don't jump out at me as being too forward at all, although they do put me a little closer to the stage than the W3.  The TF10Pro mids sound recessed and lifeless in comparison.  The UM3X's more forward mids don't seem to hurt the UM3X soundstage size, which still remains wide and deep for me.  Typically the uDAC-2 amp has a slightly smaller and more forward soundstage than my opamp rolled iBasso D4 or D10, Pico Slim or Amphora, but the midrange presence is still just about right when any of these amps are paired with the UM3X. 
 
I'm always looking for synergy with my source/amps, so I tried a few (but not all of them yet).  Switching to the Pico DAC > Protector amp with balanced TWag cable, I find the sound to be slightly more aggressive than via the uDAC-2 (due to the amp), along with a slightly bigger sense of space or separation.  I've heard this same aggressiveness in the Protector with other phones as well, and it sounds better with HD600 than HD800 for example.  Strangely, the Protector's slight aggressiveness in balanced mode is improved when using single ended mode, but the power and soundstage suffer in single ended mode so I don't typically use single ended mode.  While I think the Protector is a better match for other phones that benefit from it's more aggressive sound signature, it's still enjoyable with the UM3X - just not as much.  My ALO Amphora is also plugged into my Pico DAC-only, and I moved the UM3X back and forth between Protector and Amphora a few times.  The Amphora single-ended simply sounds better with these IEM than the Protector, and again I can recommend this amp/IEM combo without reservation.
 
Plugging the UM3X back into the uDAC-2 again while still using the balanced TWag cable (with single ended adapter) the UM3X sounds a little more detailed than it did with the stock cable before.  It seems to me that the TWag cable is a worthwhile upgrade for the UM3X for some extra micro-detail, although the stock cable isn't bad at all and cables are the last upgrade you should seek after finding a good IEM, source and amp.  The TWag cable is a good reason to get the UM3X with removable cable, while the Protector's balanced soundstage is just an added plus.  If you get a TWag cable, you should consider a balanced cable with the single ended adapter, so it's more versatile in the future.  You can even get an adapter to let you use the Protector version of the cable with the new iBasso balanced amp.
 
Moving the UM3X over to my iPhone 4 > TWag LOD > Pico Slim also made me really happy.  The UM3X sound like they were made for the Pico Slim.  I believe the Slim was voiced with ES3X, and just like with my ES3X the UM3X really shine with the Pico Slim (while the Protector stands out with my JH13Pro, UE11Pro, or HD600 and HE-5/5-LE).  The bass depth and power with the Pico Slim is improved over the iPhone 4 headphone out, which wasn't bad until I directly compared the two.  The treble extension and space is also improved with the Pico Slim, and the overall presentation is more refined and immersive sounding.  The Protector in single-ended mode sounds closer to this than it does in balanced mode (I don't know why), but I still give the nod to the Slim (or uDAC-2).  Nevertheless, the Amphora that I mentioned above is even better with these.  But for portable use, the Pico Slim is my favorite amp for the UM3X.
 

 
I wondered about frequency response, and as an after thought I pulled out "Bink Audio Test CD" and ran frequency test tones.  With most amps my 48 year old ears can hear from 16Hz to 16Khz with the UM3X.  With the uDAC-2 I found there was a small bump at 2500-3150Hz that isn't there with the single-ended Protector or Amphora (likely the amp), and another at 6300-8000 that was there with the Protector and uDAC-2.  However, the Amphora was fairly rolled off for the 16Hz tones, and the only peak I heard was at 8Khz.  This is similar to what I heard with the ES3X last time I checked.  Although this 6-8K range is in the sibilant frequencies, the UM3X have no sibilance boosting properties.  Sadly, the Protector amp seems to distort with the 16- 32Hz tones (only did this single-ended), but the uDAC-2 and Amphora were clean (this was with a full charge and plugged into the wall). 
 
SUMMARY:  There is no doubt that I would pick either of these IEM over my old IE8 and most other universal IEM.  But after adjusting to the UM3X sound, I actually may prefer the UM3X just a little more than my W3, at least with certain recordings and the right tips.  For instance, after listening to Bill Evans "Waltz for Debbie" with the UM3X, switching to the W3 made the string bass stand out more than the piano, and the venue sounded a little more hollow and "echoey" to me with the W3.  On the other hand, with Led Zepellin "Mothership" or Pink Floyd "Animals" the W3 seemed a little more punchy and fun to rock out to.  
 
And switching the W3 to Complys tips or my UM56 custom tips seemed to level the playing field a little more than when using silicone single flange tips on both. The W3 I used are the limited edition #82/333 with the gold logo instead of red logo, but they sound the same as the regular W3 that are out on loan (I've compared them).  In the end, if you are looking for an accurate, detailed and transparent universal IEM, with a removable cable that can be upgraded or balanced, with good isolation and comfortable fit, then look no further than the UM3X.  I still think my W3 are up near the top, but maybe they're not as good of an all around "jack of all trades", nor quite as accurate as the UM3X are when you are forced to use universal tips with them.
 
Just for fun, a photo of the Westone 3 Limited Edition:

I've had the Brainwavz M2 here for several weeks, and I'm sorry that I haven't had the time to post my thoughts on them sooner, but I'm doing so now after enjoying them the whole time.  My Star rating is against other IEM in the $100 and under range.  I received these as a free review sample, but they did not buy any special favors.
 
The build quality is not bad for a budget IEM. The cable feels nice and is fairly tangle free, as well as having only a small amount of microphonics. I did have an issue where the strain relief on the right earphone came loose and would slide up and down the cable, and for a while I left it that way as it helped me identify the right and left by feel in the dark. Eventually I glued the strain relief back in place. While doing that I discovered that the metal rod that the cable runs through could be unscrewed too easily from the earpiece.
 
Isolation with single flange silicone tips is decent like my Nuforce IEM with Shure tips, and more than my RE252, but less than my W1 with triple flange tips. They isolate enough to enjoy the music while sitting 3 feet way from a window air conditioner unit. They also came with a variety of tips and a nice case, but the medium silicone tips worked right away for me and I didn't bother with the rest.
 
GEAR USED: MAcbook Pro lossless music > Pico DAC > ALO Amphora, Macbook Pro > uDAC, uDAC-2 or DACport, iPhone 3GS and iPhone 4.
 
EARPHONES COMPARED: Brainwavz M2 vs Brainwavz Beta, HiFiMan RE-2, Nuforce NE-6/7M, Maximo iMetal iP-HS-5, Denon C700, Westone 1, Westone 2, Westone 3, Monster Turbine Pro Gold, UE11Pro.
 
MUSIC USED: (24/96 only where noted, otherwise 16/44 lossless):

* Diana Krall - Live in Paris
* Peter Asplund - As Knights Concur
* John H. Clarke - Acoustic Guitar (bought off CDBaby.com)
* Nils Lofgren - Acoustic Live
* Tord Gustavsen Trio - "Restored, Returned"
* Esbjorn Svensen Trio - From Gagarin's Point of View
* Jimmy Cobb Quartet - Jazz in the Key of Blues 24/96
* Shelby Lynn - Just a Little Lovin
* Nancy Bryan - Neon Angel 24/96
* Wendy Sutter - Songs & Poems For Solo Cello
* Eva Cassidy - Live at Blues Alley
* Ottmar Liebert & Luna Negra - Up Close 24/96
* Bill Evans - Waltz for Debby
* Carla Lother - 100 Lovers 24/96
* Infected Mushroom - B.P. Empire
* Bella Sonus - Enamoured
* Jack Johnson - In Between Dreams, On and On, and Sleep Through the Static
* Pink Floyd - Animals
* Orianthi - Violet Journey
* Black Eyed peas - The E.N.D.
* Katy Perry - One of the Boys
* Sade - Soldier of Love
* A variety of low bit-rate rock music downloads for my kids to look for issues
 
SOUND: I felt that they sound pretty nice right out of the box. They seem to have raised the bar for what I consider to be budget earphones. After just an hour of listening I was ready to say that these could easily sell for twice the asking price, and are a lot of fun to listen to. They made small improvements in refinement and bass control over the first 100 hours, but one could start enjoying them right away.
 
If I'm trying to describe the sound, it helps to compare them other earphones or headphones. I might call them the Denon D2000 or D5000 of the IEM world, but that may not be a perfect match as I'm working from memory of the Denon. The M2 frequency response was almost a perfect match for my UE11pro customs, minus the UE11pro's superior detail, air and extension in the highs, refinement and speed. But even the soundstage size seems to be of similar proportions. I actually went back and forth between my UE11Pro and M2 out of several amps after I heard this, and the biggest difference in the frequency response of the two is that the M2 are slightly darker or recessed in the highs than the UE11Pro. No, I'm not saying the M2 are as good as an over $1100 custom IEM, but if someone wanted to have an idea of the UE11Pro "flavor" I would tell them to try the M2 to hear the tone and balance.
 
In comparison to my Denon AH-C700 which I paid $199 for in 2007, the Denon sound thin and hollow in the mids with a brighter or even "tizzy-sounding" treble, only redeemed by their nice bass presence which isn't as well controlled as the M2. The Denon lack the rich vibrant mids and refinement of the M2, and are also not as efficient. However, comparing the M2 vs the Denon or Nuforce earphones does seem to make the M2 sound a little dark in the highs; maybe more from the sudden contrast, and having acclimated to the other IEM than a fault of the M2. But if I listen to the M2 first, then switching earphones makes the Denon and Nuforce sound bright and the M2 more normal instead. The Denon improve noticeably with Complys T400 foam tips, but not enough. The M2 are more fun and enjoyable with better bass control, cleaner richer mids, and smoother more refined treble than the Denon. Impressive for the low price.
 
In previous comparisons my Nuforce NE-6 and NE-7M also topped the Denon C700, so I also compared those to the M2. The NE-6/7M are a little more neutral and forward sounding than the M2. Although they may be slightly more accurate in frequency balance than the M2, they are not as much fun and don't disappear behind the music as well as the M2 do. The M2 seems to be more transparent in the sense of not calling too much attention to the mids or highs, although the bass is certainly tipped up in a fun kinda way and the overall sound is warmer (like the UE11Pro). The more forward upper-mids of the NE-6 and NE-7M bring some of the details of the background instruments out, but not necessarily in a way that allows the earphones to disappear when listening. This improved in the Nuforce earphones by switching from the stock tips to some Shure E2c tips, but not enough to overcome this.
 
Similarly, the Maximo iMetal iP-HS-5 (aka i590 for iPhone) and HiFiMan RE-2 were a bit colored in comparison, with a tilt toward the highs and details rather than the warm mids and bass of the M2. Although I have rated the Maximo on par with the Nuforce or HiFiMan RE2 (just with a different sound), and above the JVC Marshmallows and Aircushions or Brainwavz beta, they still fall below the new M2 for me when it comes to enjoying the music instead of listening to the earphones' sound. The area where the good budget IEM like Maximo or Nuforce surpass the M2 is in their bass detail and speed, but I prefer the additional impact of the M2 and less attention to detail when I want to have some fun with them. This was especially appreciated with low bit-rate downloaded music that my kids listen to.
 
I decided to compare the M2 to my Westone 1, since I hadn't listened to them in a while. They cost several times more than the M2, but I was running out of budget IEM to compare them to. I found the W1 to be better in neutrality, transparency and speed, but they were not as extended in the deep bass or treble as the M2. The M2's bass quantity is a bit higher and more impactful than the bass of the W1, but the W1 bass speed and definition is still noticeably better. Despite less bass presence than the M2, the W1 are a fairly warm sounding IEM and not out of character when comparing them to the M2. Their mids and highs were somewhat similar in volume, up to the limits of the W1's balanced armature. But the M2 have a little more sparkle/air/extension and a larger more spacious soundstage, while the W1 are more forward/intimate sounding and slightly muted in the ambience department.
 
The W1 are pretty good for single BA IEM, and they disappear better than the M2 or others when I listen to jazz and acoustic or string music, but the M2 were more fun for rock music or for listening loudly. For critical listening the W1 are a better choice, and more accurate most of the time. I wouldn't call the W1 a "fun" phone like the M2, and some listeners have described them as flat or boring at times. But the W1 also sound best when amped, while the M2 are less picky about that, and with a good amp the W1 shine better. Certainly the M2 can be more exciting and dynamic to listen to than the W1, especially unamped, but a similar thing could be said about the D2000/5000 vs the HD600/650. Being more fun with less power doesn't always make it a better choice for critical listening.
 
When bringing out the Westone 2 and 3, or even the Monster Turbine Pro Gold, the M2 began to sound more like a budget IEM. The M2 bass is more like the W3 or MTPG in quantity, but not in quality. And they just don't have the speed, detail or realism of the more costly IEMs that I tried.
 
SUMMARY: The Brainwavz M2 (aka Visang R03) are a nice sounding budget IEM which have a pleasing tone, fun bass impact, and good soundstage/image. They are a very clear upgrade to the wwww.MP4nation.com Brainwavz Beta that I reviewed previously, as well as more enjoyable than several other $40-$150 earphones that I own. They are not as accurate, fast or detailed as my balanced armature IEM or some of my dynamic IEM, but I also would not call them slow or veiled. Their biggest problem is with the slightly boosted bass that is somewhat less well controlled than I would like. They're not a giant killer and the sound is not perfect, but they don't do many things wrong - there are no big irritating peaks or troughs that would bother even the more discerning listeners. For those on a budget it would be well worth giving these consideration.  

I received the HE-5 LE about 7 weeks ago and I've been dying to post a review on them. But I haven't been feeling well lately and it took me longer than usual to put my thoughts together. I'm sorry this is not as organized and coherent as I would like it to have been, but I can't delay posting this any longer.
 
As they arrived: 
 

 
INTRODUCTION:  I probably have about 400 hours on the HE-5 LE right now, with about 250 being 24/7 burn-in and 150 hours from listening to music or movies. I want to start by saying that during this time the HE-5 LE have become my "go to" daily listening phones for over 6 weeks now. I'll also say right away that while they are not a "giant killer" I prefer them over just about anything else that I have heard in this price range or less. In addition, they are not totally embarrassed by headphones costing much more.
 
The HE-5 LE are an evolution of the original HE-5 that were released November 2009 with a wooden driver housing and silver plated copper cable. When I first received the original HE-5 I found them to be an excellent headphone, and felt that they surpassed my more costly Grado RS-1 with APS V3 cable. With the Grados and flat pads the soundstage was somewhat 2D sounding and more of a "wall of sound" vs the HE-5 which had a bigger soundstage and sounded more open and transparent. Speed and detail seemed similar in both, being above that of my APS V3 cabled HD600 or stock Gradp HF-2 which sounded almost sluggish and veiled in comparison.
 
The RS-1 had a slightly rolled off or muted treble with the flat pads, but the quality of the mids and bass with flats was similar to the HE-5. In contrast, my original HE-5 have a much crisper and present treble, and in my case there is no hint of sibilance like others have reported. Switching the RS-1 to bowl pads improved their soundstage and treble sparkle, but made them sound thinner in the mids and lighter in the bass - areas where the original HE-5 excel over the RS-1/Bowls. My only complaint with the original HE-5 was the slightly nebulous or indistinct imaging of individual instruments, and I found them just a little lacking in the sense of weight or body to the mids.
 
Some people liked the HE-5 more than the HE800 while others complained of the treble being bright or sibilant, and a few people had the wood housing crack (likely due to changes in humidity). I have had no such problems and still have the original HE-5 while the re-cabled RS-1 are long gone. Head-direct set out to address the few complaints about the original HE-5, and I think that they accomplished what they sought to do when they released the HE-5 LE. 
 
GEAR USED: A Large part of my recent Luxman P-1u review was done using the HE-5 LE, and you might want to read that as well. The Luxman mated very well with these phones and had slightly better treble extension than my ZDT amp, which otherwise matches the Luxman P-1u performance in all other areas. So, the HE-5 LE have been treated to being used with a couple of the best amps out there, in order to find out their true potential. I don't think that they were held back at all by the gear used, and they still work very well with lesser gear as well.
 
In my main rig I used a Samsung DVD > Synergistic Research active shielded coax cable > PS Audio Perfectwave DAC > anti-cables XLR and RCA IC > Luxman P-1u or Eddie Current ZDT. I also used my Macbook Pro as source via optical out > Emotiva and sysconcept.ca optical cable. And I used an Apple 802.11n only Airport Express at 5Ghz with this rig to connect to my iTunes library on my iMac (which seems to have no stutters or drop outs). I used a simple APC computer UPS which does a good job keeping everything quiet.
 
In my bedroom rig I used my Macbook Pro or Marantz CD5001 > Apogee mini-DAC > maxed Woo WA6 and SAC KH1000 amps, as well as EF-5 amp and Nuforce HDP. I also tried them with some portable solutions including a CEntrance DACport, RSA Protector with balanced 4-pin XLR TWag adapter, iBasso D4 and ALO Amphora.
 
MUSIC USED: (24/96 only where noted, otherwise 16/44 lossless):
 
* Diana Krall - Live in Paris
* Peter Asplund - As Knights Concur
* John H. Clarke - Acoustic Guitar (bought off CDBaby.com)
* Nils Lofgren - Acoustic Live
* Tord Gustavsen Trio - "Restored, Returned"
* Esbjorn Svensen Trio - From Gagarin's Point of View
* Mattias Svensson Bill Mays Joe La Barbera - Head up High
* Sara K. - "Hobo" 24/96
* Jack Johnson - In Between Dreams, On and On, and Sleep Through the Static
* Jimmy Cobb Quartet - Jazz in the Key of Blues 24/96
* Shelby Lynn - Just a Little Lovin
* Nancy Bryan - Neon Angel 24/96
* Joel Styzens - Relax Your Ears (bought off CDBaby.com)
* Wendy Sutter - Songs & Poems For Solo Cello
* Bob James Trio - Straight Up 24/96
* Eva Cassidy - Live at Blues Alley
* Ottmar Liebert & Luna Negra - Up Close 24/96
* HDTracks.com - Open Your Ears (variety) 24/96
* Bill Evans - Waltz for Debby
* Carla Lother - 100 Lovers 24/96
* Infected Mushroom - B.P. Empire
* Pink Floyd - Animals
* Led Zepelin - Mothership
* Bella Sonus - Enamoured
 
HEADPHONES COMPARED: In addition to comparisons with my original HE-5, I compared the HE-5 LE a wide variety of headphones, including re-cabled HD800, AKG 600 ohm K240M, K1000, Smeggy SFI ortho-pucks, HD600 with APS V3 cable, Lawton Audio modded D7000, Grado HF-2, ATH-ESW10 and Sarn modded ATH-A900. I did not re-install the stock HD800 cable, since it adds some upper mid/treble colorations of the headphone and would make the HD800 an inferior tool for comparing to the performance of the HE-5 LE.
 
FEATURES and SPECS:
 
Price $699
Planar Magnetic driver
Plastic driver housing with leather wrapped headband
OFC removable cable with 4pin XLR (same to K1000), and XLR to 6.5mm converter
Frequency Response: 10 Hz to 60 KHz
Sensitivity: 87.5 dB, 1 mW
Impedance: 38 Ohms
Weight: 402 g, without cable
And an included wood presentation box (seen below)
 

 
INITIAL IMPRESSIONS:  The first thing I heard with the HE-5 LE out of the box was their improved and more cohesive imaging, with better weight and body to the reproduction, especially in the mids which I think are a bit better than the original. Like their predecessor they don't isolate outside noises at all, and everything comes through. Unlike their predecessor there is no wood to be found anywhere on these. They do seem to be very professionally made, and on par with other large scale production headphones by the "big guys". I also found the LE velour ear pads to be softer and they conformed to the shape of my head better than the originals - so they fit better and feel a little more comfortable to wear. Clamping force is just fine, but I do have to wear them with the headband at the smallest settings despite an average sized head. The decrease in weight vs the original HE-5 was also noticeable, and appreciated when wearing them.
 
Vs the original HE-5 the differences in sound were not as big out of the box, but I noticed them right away and the improvements increased through burn-in, which resulted in a more refined and complete sounding headphone in the end. Since I felt that the HE-5 LE sounded slightly fuller/richer in the mids than the original, this gave me a little better feeling of being in the same room with the recorded piano than with the original HE-5. The different harmonics and keys on the piano seem to have a more cohesive body and point of origin, rather than being slightly nebulous in origin and space. And at high volume levels I thought the LE were indeed less fatiguing in the treble than the original HE-5 which have hundreds of hours on them, all the while retaining all the great things that I posted about liking in the original (like the detail, sparkle and impact). However, there was a sense of slightly more space or openness in the original HE-5, where the LE seemed a little more constrained or intimate sounding than the original (until I removed the grill clothe later).
 
COMPARISONS:  I then compared them to my re-cabled HD800, with the LE and HD800 both plugged into my SAC KH1000 amp at the same time. The amp has a 4-pin for K1000 phones plus a 1/4" jack and there was no change in amplification quality with both phones vs only one at a time. So I used this amp initially to compare them. In comparison of the two phones I thought the HD800 were a little more fatiguing with moderate to loud volume levels of jazz trumpet music (Peter Asplund), in exchange for a bigger more spacious soundstage. The HD800 just don't like being paired with a bright amp like the SAC. The HD800 excel because of their extraordinary clarity and soundstage, where the sound doesn't seem to come from a little speaker next to the ear, but rather the sound seems to come from outside the headphones. The LE seem to have more of a wide and deep in-the-head "head-stage" combined with some out of the head imaging, for an overall more intimate presentation. With the SAC amp I would say the HD800 are more detailed and aggressive, but to me the HE-5 LE don't seem to lack much in the way of detail or liveliness except when in direct comparison to the HD800. With quick switching back and for the contrast between the crispness of the HD800 and smoothness of the HE-5 LE is more apparent. After this I started looking at amplifier synergy along with my comparisons, and a lot of the following discussion covers how they sound with different amplifiers.
 
Moving the HD800 over to the Woo WA6 and comparing them again to the HE-5LE/SAC amp combo, the HD800 improved noticeably but I thought the 800's were still a little more fatiguing with some music than the HE-5 LE once the volumes get very loud. This was less of an issue when moving the HD800 to the ZDT amp. So, with many amps the frequency response of the HE-5 LE is a little more balanced than the HD800, and the HE-5 LE are more forgiving of the choice of amplifier as well. I love the huge soundstage of the HD800, but it quickly seemed that there would be some things that the HE-5LE would be better at. For example, I switched to Fourplay "Between the Sheets" and the bass line with HE-5 LE was more visceral and punchy, and close to that of the LA7000 (but less than the O2 Mk1 and maybe a stock D7000). With loud rock music the HE-5 LE seemed more suited to the task than my HD800, unless I used the HD800 on the ZDT amp. The LE were also less fatiguing with loud rock music than the Grado HF-2, as well the original HE-5.
 
The HE-5 LE on the SAC amp can play a good bit louder than with the Woo WA6 amp. In comparing both phones on the Woo WA6, the HD800 will play louder than the HE-5 LE with that same amp but both could use a little more impact. But switch the LE over to the SAC, EF-5, ZDT or Luxman amplifiers and the HE-5 LE take on a new level of impact, power and energy. So, the amp you use to drive the HE-5 LE can still be important. Meanwhile the HD800 don't sound nearly as good on those other amps as they do one the ZDT or Luxman. Despite the lesser power, I still felt that the HE-5 LE sounds very nice and balanced with the WA6. While the WA6 doesn't have the impact and power of the EF5 or SAC amps, it has enough juice that I would not be maxing out the WA6 very often if I was using it as my primary amp for the HE-5 LE. Power isn't everything and the tonal balance and soundstage with the WA6 was very good. The LE responded similarly with the ALO Amphora, in sound and power levels, and like the WA6 it was adequate but at the lower end of what I would recommend for these headphones.
 
Heck, if absolutely needed I can actually drive the HE-5 LE with an iBasso D4 portable amp or CEntrance DACport, but that would not be my first choice as they are less powerful than the WA6. Headphone efficiency seems close enough to the original HE-5, but it's slightly easier to drive the LE with some portable amps because it doesn't seem to demand as much current from the amplifier. Underpowered amps sounded less strained when pushed to the limits with the LE vs trying the original HE-5 on them, but I would not be happy driving them with a typical 5v portable rechargeable amp. Oddly, the HiFiMan HM-801 actually seemed to have some difficulty driving the HE-5 LE, while it had no trouble at all driving the 300 ohm HD600 and HD800.
 
In previous testing the SAC amp was better with my K1000, while the EF5 was better with HE-5; but the LE seems to do well with either amp. I did prefer the RCA cleartop tube with the LE, while I was using a Mullard for the original HE-5 or HD800 (can't find my tung sol black glass 12AU7). The SAC and Nuforce HDP amps do give the LE a little bigger soundstage than the EF5, although their soundstage is still slightly smaller than when using the Woo WA6 (which has a smaller soundstage than the ZDT or Luxman). All of these amps had more power for the LE than the WA6 or Amphora. The ZDT and Luxman sounded very similar to each other and were the best amps for the HE-5 LE, giving them a combination of bigger soundstage and better impact that I don't get get at the same time with my lesser amps. I would say the LE soundstage has good depth and width, although it's a little more forward/intimate and less deep/wide than my HD800/HE60 or K1000. I'd say it's soundstage is almost as big as the O2 Mk1, HD600 or LA7000 (and it's bigger than HF-2 or ESW10).
 
I thought the Nuforce HDP amp sounded good with HE-5 but it's even better with the HE-5 LE, as is the RSA Protector and ALO Amphora - but the HE-5 LE still really shine with a high-end amp like ZDT or Luxman. While the HDP seems to have more power for the LE than the WA6, it's just a little less than the SAC or EF-5. The Protector and Amphora were closer to the power of the WA6, and still adequate - surprising considering they are both battery driven. Even with the DACport and D4 I would not typically listen at higher than 75% on the volume, because the HE-5 LE are easier to drive than the original HE-5. The HE-5 LE actually sounded better with the DACport or Protector than the HD800, where the HD800 seemed more underpowered with the DACport and a bit bright with the Protector.
 
When reviewing the Luxman P-1u amp I also did a lot of comparison between the HE-5 LE and the Stax O2 with the WES amp. The Stax O2 Mk1 excel because of their transparency, detail and their solid foundation in the bass lending weight to the instruments. The HE-5 LE with grill clothe removed come closer to the detail but not the transparency of these flagship headphones. The LE come close to the soundstage and headstage size of the O2, but they sound a little thinner than the O2 although fuller than the HD800. The un-modded LE on the Luxman P-1u seemed to be a little more balanced and neutral than the O2/WES, with a little more treble extension; but they still had less weight in the bottom-end and less transparency overall. The Stax O2 still gave a better sense of being there at the performance, but with the WES amp the O2's bass can also be a little more prominent than is necessary. On the other hand, the Sennheiser HE60 on the WES are also very balanced sounding and can easily top the HE-5 LE at normal listening volumes. But like the HD800, the HE60 can sound a little fatiguing at high volumes and they cost me 3x more than the HE-5 LE.
 
So, overall I'd say the HE-5 LE frequency response is very balanced sounding, but leaning towards the "warm side". I was happy with the bass, mids and treble although I might have wished for slightly more bass weight when the grille clothe is removed, or more treble sparkle, extension and transparency when the grill clothe is in place. The descriptions below were with the stock cable and grill clothe in place, and then I'll further discuss the changes with different cable and grill clothe removal.
 
BASS: The LE's bass is tight and fast, without bloat or one-note bass. Bass detail is good. The LE plays strong to 25Hz when checking with test tones, and 20 Hz is maybe only 2-3 db down from that. Bass impact is greater than that of the HD800 and less than that of my O2 Mk1 with WES, so it's fairly close to the impact and quantity of my LA7000 although not quite as strong at 20-30Hz. If I had to guess I would say that the LE have less bass weight than a stock D7000 would have, but more than the HD600/800. I don't think the LE take away from or add to the bass when the grill clothe is left in place. They can be appropriately punchy and weighty when called for when using an amp with good current reserves like the SAC, EF5, HDP or ZDT. With the WA6 or Amphora the bass impact is a little softer although they never sound thin with those amps.
 
MIDRANGE: Instruments and voices have very good timbre and tone. Vocals are rich and involving, and seem firmly grounded. I did not hear any unwanted peaks or troughs with test tones from Bink Audio Test CD. I felt the mids to be slightly forward sounding but not overly so, and maybe closer to that of the presentation of the HD600 (i.e. less forward than the HF-2). Listening to the HE-5 LE for a long time and then quickly switching to my Grado HF-2 reveals just how colored my HF-2 are, which sound a little nasally in the mids after hearing and adjusting to something much more neutral. I can switch from the HE-5 LE to the K1000, HD800, LA7000 or O2 Mk1 and not feel like I have much adjustment to make to the new sound (my re-cabled HD800 are not as bright as with the stock cable).
 
TREBLE: The treble is ever so softly muted in comparison to the original HE-5; but I don't feel that it's lacking, and in comparison to my Stax O2 Mk1 they are not as dark sounding as the O2 (even with grill clothe in place). They have a nice sparkle to the sound, and cymbals ring true. I can hear out to 16Khz with them using my 48 year old ears, although the 12Khz and 16Khz tones sound a bit quieter than the 10Khz tones where I believe I can hear a peak in the frequency response. I could not hear a 6Khz - 8Khz peak to contribute to sibilance, and even my sibilant recordings from Diana Krall or Kathleen Edwards sounded good with the LE.
 
MODIFICATIONS: After reports of the LE improving with the original HE-5 cable, or with the grill clothe removed, I tried both of those mods after the headphones had over 250 hours on them. I did find improved treble presence with the silver plated copper cable of the original HE-5. This could lead to the sense of better detail even though it wasn't really that much more than with the original cable. It's possible that there was slightly more micro-detail, but I think it was more of an improvement in the tone than detail. I wanted to use the stock LE cable with 4-pin XLR plug on my SAC and ZDT amps, so I tried removing the grill clothe next. This also increased the treble energy a small but noticeable amount, but also resulted in the sense of better transparency and openness to the sound.
 
There was a small reduction in bass impact and weight with the grill cloth mod, but this only brought the bass to be slightly less than the LA7000 and still more than that of the HD800. I prefer the bass and lower-mids weight with the grill clothe in place, and the highs with the grille clothe removed. If I had an especially dark sounding amp or source I might use both of these mods at the same time, but otherwise I did not feel the need to do that.
 
In comparing the modded LE to my AKG K1000 I found the LE's mids and highs to sound almost identical in richness and detail; and while the K1000 were more open and had a larger soundstage, the HE-5 LE sounded much more natural and realistic in the bass region. The LE bass detail, speed and impact was noticeably better than the K1000, to the point that I could live with the smaller soundstage since the mids and highs were just as good. With the grill clothe in place and the original HE-5 SPC cable I still prefer the HE-5 LE over the K1000.
 
Previously I mentioned that the LE are not a giant killer, but I think the K1000 are just a little over-rated, after hearing two different pairs on a variety of headphone and speaker amps. They have great mids and highs, but they just don't seem to have the focus and detail in the bass that a high-end headphone should have. I simply preferred the HE-5 LE over my K1000 driven by ZDT or SAC KH1000 amps.
 
The modded LE's mids and highs are also very similar to that of my LA7000 with bubinga wood cups and Jenna Labs cable, although the LA7000 further improve upon the LE's bass (and they don't sound like closed cans). And the LA7000 have a little better lower midrange presence than the LE unless I replace the grill clothe. But if I replace the grill clothe then the HE-5 LE don't compare as well in the highs or sense of openness; although they gain back the lower mids and bass impact/control and move closer to the LA7000. Some people may be willing to sacrifice this small amount of bass impact/control for the improved transparency, especially since the bass is still more than adequate with the modification. Other's may find using the SPC cable to be the better option.
 
I keep switching back and forth and haven't decided on my favorite configuration yet. Right now I have the grill cloth re-installed with the stock cable, using them on the SAC amp. The beauty of these is that I can mix and match the mods on a whim, or even add more dampening under the grills if I wanted to improve upon the bass even further. In the future I'd like to try the Smeggy mod, along with the original HE-5 SPC cable or a balanced APS V3 cable someday, and maybe even a new material for the grill itself. 
 
(with stock cable but grill clothe removed):
 

 
CONCLUSIONS: The HE-5 LE seem to be a refinement and improvement over the original HE-5, but not such a big change that Head-Direct would want to continue selling the old model at the same time. I love the wood cups and wood sliders on the original, and am sorry to see that part discontinued, but I can see how the new materials would be more reliable and long lasting. I also think the 4-pin XLR cable with single ended adapter is a great move, and many audiophiles will welcome this change. They will still have people who want a shorter lighter or thinner cable, or a brighter sounding cable. Since they can't make everyone happy with just one cable, they started offering people the option to buy these cables separately if you email them.
 
After spending several weeks with the HE-5 LE, I can honestly tell people who can't afford the LA7000, or HD800 with a nice amp and aftermarket cable (or Stax O2 Mk1 with SRM-717 or better) to consider the HE-5 LE as their next choice.  My HD800/ZDT amp and O2/HE60/WES amp are down in my basement so I don't get to listen to them as much as I do the HE-5 LE in my bedroom rig. I don't like carrying headphones up and down the stairs, where I often forget where I left them or can't find them where I need them to be when I want to have a listen. I prefer to pair a set of headphones with a particular rig, so I am perfectly happy to listen to the HE-5 LE upstairs where I spend a lot of my time being closer to my family (and other times I do want to hide in the cave with my big headphone rig).
 
The cheapest headphone to come close to replicating this kind of sound is the $699 SR-404 Limited Edition, which is sold out as new and hard to find used. I don't feel that the RS-1 or stock D7000 perform quite as well as these - those are still good options to consider if you must, but I feel that they both need to be modded to be able to catch up or pass these up. In my case I simply prefer the HE-5 LE, which are a good compliment to my HD800 for when I want something a little different or want to listen without my ZDT amp.
 
My Grado HF-2 and Sennheiser HD600 don't get any ear time at all these days, because I'm enjoying the detail and speed of the LE more.  And I'm enjoying the HE-5 LE/SAC amp more than my SR-Lambda/eXStatA combination in the bedroom.  My ATH-ESW10JPN remind me a bit of the HE-5 LE, but the LE still have more detail, speed, soundstage and bass impact. When I need isolation I grab the LA7000, but during the summer the LA7000 are hotter and not as comfortable to wear as the LE. The K1000/SAC amp used to be my bedroom summer headphone rig, but the HE-5 LE have now replaced the K1000 permanently. I think that is a strong testimony to how much I enjoy using the new HE-5 LE so far.

 

 
LUXMAN P-1u REVIEW:
 
I just finished spending 2 weeks with the Luxman P-1u headphone amplifier from Todd @ TTVJ and this amp was a pleasure to listen to.  I just shipped it back two days ago, but if I didn't already have an Eddie Current ZDT amp then I would have been sorely tempted to try to buy the Luxman which ranks among the best dynamic headphone amps that I have tried.  Thanks for the opportunity Todd!
 
GEAR:  I used a Samsung DVD > Synergistic Research active shielded coax cable > PS Audio Perfectwave DAC > anti-cables XLR and RCA IC > Luxman P-1u > HD800 with Locus-Design Hyperion cable.  I also used my Macbook Pro as source via optical out > Emotiva and sysconcept.ca optical cable.  And I used an Apple 802.11n only Airport Express at 5Ghz to connect to my iTunes library on my iMac (which seems to have no stutters or drop outs).  I used the Luxman power cord that came with it, plugged into a simple APC computer UPS which does a good job keeping everything quiet.  I'm sad to say that I didn't use my vinyl rig as source because I had to return my Nighthawk in order to pay for a dental implant. My cheap GEMsound phono preamp is not up to the task and doesn't perform well with my Benz Micro ACE Red L moving coil cartridge.  It was too much trouble to reinstall my Ortofan Blue MM cart for my current preamp since I plan to either get another nighthawk or a TTVJ phono preamp later. In the photos you'll see that the TT made a good stand for setting up the P-1u.
 

 
MUSIC (24/96 only where noted, otherwise 16/44 lossless):  
 
* Diana Krall - Live in Paris
* Peter Asplund - As Knights Concur
* John H. Clarke - Acoustic Guitar (bought off CDBaby.com) 
* Nils Lofgren - Acoustic Live
* Tord Gustavsen Trio - "Restored, Returned" 
* Esbjorn Svensen Trio - From Gagarin's Point of View 
* Mattias Svensson Bill Mays Joe La Barbera - Head up High
* Sara K. - "Hobo" 24/96
* Jack Johnson - In Between Dreams, On and On, and Sleep Through the Static
* Jimmy Cobb Quartet - Jazz in the Key of Blues 24/96
* Shelby Lynn - Just a Little Lovin
* Nancy Bryan - Neon Angel 24/96
* Joel Styzens - Relax Your Ears (bought off CDBaby.com)
* Wendy Sutter - Songs & Poems For Solo Cello
* Bob James Trio - Straight Up 24/96
* Eva Cassidy - Live at Blues Alley, Time after Time
* Ottmar Liebert & Luna Negra - Up Close 24/96
* HDTracks.com - Open Your Ears 24/96
* Bill Evans - Waltz for Debby
* Carla Lother - 100 Lovers 24/96
* Infected Mushroom - B.P. Empire
* Pink Floyd - Animals
* Led Zepelin - Mothership
* Bella Sonus - Enamoured
 
HEADPHONES:  In addition to the re-cabled HE800 above, I tried a wide variety of headphones and IEM with it, including my difficult to drive AKG 600 ohm K240M, K1000 and Smeggy SFI pucks, the easier to drive HD600 with APS V3 cable, HiFiMan HE-5 LE and original HE-5, and my very easy to drive LA7000 and HF-2, along with my very sensitive and low impedance JH13Pro custom IEM with TWag cable.  I did not bother to re-install the stock HD800 cable, since it adds some upper mid/treble colorations of the headphone and would make the HD800 an inferior tool for assessing the performance of the P-1u.  The HD800, HE-5/5LE, LA7000 and JH13Pro were the best phones for assessing the performance of the P-1u, while the others had some weakness or coloration that rendered them less useful.  Nevertheless, the P-1u was able to drive all these headphones well, and there is not another amp in the house that these phones work better with (with the exception of the K1000).
 
COMPARISONS:  I compared the Luxman side by side to my Eddie Current ZDT, maxed Woo WA6 with pseudo dual power supply and Sophia Princess 274b rectifier, ALO Amphora, and Nuforce HDP.  After trying four different 12AX7/5751 tubes in the ZDT over the past year, I settled on the Sylvania gold pin 5751 as having the most natural and extended treble while sounding more refined than the stock Mullard re-issue 12AX7.  For A/B comparisons I could plug the PWD XLR out into the Luxman and then use the PWD RCA out to feed the other amp, and then listen to two amps with the same source at the same time.  This allowed for quick switching between amps using one headphone, after volume matching with my Radio Shack SPL meter.  I have also tried the PWD's RCA output into the Luxman and compared that to the XLR input, with little differences in sound quality between the two. Finally, I also tried the Luxman's RCA loop-out into the ZDT and compared it to the RCA loop-out on my Woo WES, and found them to both be quite good in sound quality with little difference from directly out of the PWD.  
 
As per requests, I also compared the Luxman with several dynamic phones to my WES with Stax O2 Mk1; where the HE-5 LE were the closest to Stax in terms of sound signature and soundstage but the HD800 closest in terms of detail and speed.  However, the Stax rig gave me all that in one headphone (minus the HD800 soundstage), but with the addition of a bit more bass in return for slightly less but more than adequate max volume.
 
FEATURES:  The Luxman P-1u may at first seem to offer few features or bells and whistles, as it doesn't seem to be loaded up with knobs and buttons, but that is not the case.  Like my ZDT it has multiple inputs, but while the ZDT has 3 RCA inputs, the P-1u can accept one RCA and one XLR input which you can switch between.  Even though the P-1u doesn't offer a balanced output like the ZDT, having the XLR input is better for when your source only has XLR out (Neko DA100 DAC or some phono preamps for example).  The ZDT uses output transformers to convert the signal into a balanced output, but if I want to feed a balanced signal into the ZDT I have to use an external input transformer, which introduces an extra set of interconnects and transformer into the mix.  
 
Both the P-1u and ZDT allow connecting two sets of headphones at the same time, without any reduction in sound quality.  However, the P-1u has two 1/4" jacks while the ZDT has one 1/4" and one 4-pin XLR jack.  Plugging in two pairs of low impedance phones into either amp did not seem to affect the performance, unlike my Sq Wave XL which used to struggle if one of the two phones was not a high impedance phone.  
 
The ZDT offers an 8-watt speaker output, while the P-1u offers an RCA loop-out instead.  The ZDT 8-watt speaker out is quiet enough to be used to drive another amplifier (according to Craig at EC), but I feel it would be dangerous to try that in real life.  So the P-1u is more useful for someone with two amps where their source only has one output, and its loop-out could be used to feed a speaker amp since it doesn't drive speakers like the ZDT.  The P-1u is more convenient to set up because the PSU is built into the main amp's case, and you don't have to find a place to hide an external PSU box where the umbilical can reach the amplifier like you do with the ZDT.
 
Finally, I wanted to comment on the quality and function of the volume pot.  The P-1u has an extremely precise volume pot for low volume listening using very sensitive low impedance IEM. I could turn the volume down to near inaudible levels and not develop a right or left channel imbalance like with some amps using a lower quality attenuator.  My ZDT and WA6 volume pots come very close to the P-1u in this regard, and the Amphora with it's stepped Gold Point is also balanced at the lowest setting, while the HDP has a noticeable channel imbalance when turning the pot below below 9 o'clock, above where listening levels are sometimes louder than desired for listening to music while falling asleep.
 
IMPRESSIONS:  I unpacked the P-1u and was immediately struck by how solid and hefty it was.  It seems built like a Mac truck, with a classy feel to the case and knobs.  I liked the combination of grey matt case with silver front panel, giving it more contrast.  At first I wasn't sure about the gold accent plate with the Luxman name/logo on it, but it grew on me very quickly.  Normally I don't go for gold accents, but it didn't turn me off in this case (you'll notice the K240M have a gold accent among silver/black theme).
 

 
When I first fired up the Luxman it sounded great right out of the box.  I can't say how much of a difference warm-up makes, but I did make it a habit to do any serious listening after it had been running for at least an hour.  I did the same with my other tube amps as well.  Never during any of the time I used it did the P-1u case become warm.  This is in stark contrast to my ZDT which becomes hot enough to cook an egg!  I can't use the ZDT in my bedroom during the summer because it heats up the room too much, so I use it in my basement where it's always cool year round.  
 
I listened to the P-1u for the first time with the HD800 and Hyperion cable, and my first thought was how similar it sounded to my ZDT and how it replicated the tube amp's sound via solid state.  Over halfway through Nancy Bryan's "neon Angel" in 24/96 hi-res I realized that I had gotten lost in the music and wasn't taking any notes or trying to collect impressions for the review.  That was a good sign, and it happened repeatedly over the next two weeks. The P-1u doesn't seem to have any sound or flavor of it's own, and does not have any qualities to the sound signature that make it an amp that would need to be limited to only certain headphones.  Like my Perfectwave DAC, I found the P-1u to have a very natural, open and transparent sound, which simply made the gear disappear, leaving just the music and whatever sound the headphones would impart. If I had to attribute a character to the sound, I would say it is warm sounding without any hint of darkness to go along with it.
 
BASS:  String bass was snappy, quick and punchy with a nice clean leading edge to the string pluck and no boomy shadow hanging over the music.  It was well defined and crisp, without any signs of "one-note" bass.  The bass impact and "oomph" was noticeably above that of my Nuforce HDP and still a little above my WA6 and Amphora, running pretty much on par with my ZDT's bass in quantity as well as quality.  Bass extension was very good, and the very deep bass line at the beginning of the first song in Bella Sonus "Enamoured" was quite present and not faded out or reduced.  
 
With loud rock or electronic music the bass did not break up and clip until very high levels that I would never listen to normally.  The bass gave a solid foundation to the presence and weight of the instruments, which the WA6 and Amphora strived to achieve but only the P-1u and ZDT could fully attain.  I noticed this with just about all my headphones except my K1000.  While the P-1u could actually attain useable volume levels with K1000, the ZDT still provided slightly more bass impact and volume with those difficult to drive headphones.  I should note that the ZDT itself is still not optimal for driving the K1000, and has never been able to match the Cavalli EHHA or the next step up to my SAC KH1000 amp in driving the K1000 (last October I did an A/B comparison of those 3 amps with K1000).
 
MIDRANGE:  I found the mids to be warm and inviting, vibrant and detailed, and not recessed at all, even with the HE-5 which are not as full sounding as the HE-5 LE.  Texture and tone of natural instruments was rich and clear, where with strings you could hear the vibration of the body of the instrument and not biased towards strings and bow like with the HDP.  Guitars sounded like they were really there, which caught me off guard a couple of times as I looked up to see if my daughter had wandered into the basement with her guitar.  Vocals were handled very well, and I could not ask for better, regardless of female or male vocals.  Like with my ZDT, when listening to a piano I had a better sense of the instrument being there in the room and taking up physical space when listening with the P-1u than with the other amps, although the WA6 and Amphora were better than the HDP in this regard as well.  The mids of the WA6 and Amphora were more forward than the ZDT or P-1u by a small but noticeable degree.
 
TREBLE:  This is the one area where the P-1u pulled slightly ahead of the ZDT in terms of sound.  I found the P-1u treble to sound slightly sweeter and more extended than the ZDT (or WES for that matter), with a more natural ring to cymbals.  I do feel that my Woo WA6 has a similar treble to the Luxman, but the rest of the WA6 sound doesn't hold up as well vs the P-1u. The ZDT and WES both have a similar treble character to each other and seem like they have more energy near 10 Khz than the Luxman, while the P-1u seems like it has more energy past the 10 Khz mark.  This was slightly supported by test tones from Bink Audio Test CD, but my hearing starts to roll off beginning at 12 Khz and is gone after 16 Khz.  Regardless, through the ZDT or WES the sound of the cymbals being hit by the drum stick seemed to be slightly more prominent at the lower treble frequencies than with the P-1u, while the cymbal strikes through the P-1u sounded a little more natural with higher frequency harmonics to my ears.  This was a subtle difference and some people might not hear it right away until it was pointed out, as the P-1u and ZDT sounded quite similar in all other areas.
 
SOUNDSTAGE and DETAIL:  The P-1u soundstage size is wonderful, and on par with the ZDT which sounded as big as the Woo WA22 with a balanced source last summer.  The lack of a balanced output does not seem to hold back the P-1u at all.  Both amps are clearly more spacious, with a deeper soundstage than the WA6 and Amphora which sounded more forward and narrower, although those two still surpassed the Nuforce HDP.  All of these amps have great detail; but air, ambience and space when listening to the P-1u and ZDT stood out above the other amps, as a demonstration of their improved micro-detail, decay and dynamic range.  Imaging was equally as good, and everything had it's place in the soundstage and headstage, without blending or blurring of instruments.  In contrast, with the WA6/Amphora instruments were squeezed closer together, and with the HDP the soundstage was even narrower and compressed in comparison to the others.
 
POWER and DYNAMICS:  The Luxman P-1u is a very powerful headphone amp with the typical headphones, and the gain is set just right for both IEM and full size headphones.  With the PWD DAC RCA output as source I would normally listen to the JH13Pro with the volume at 9 o'clock, at 10 o'clock with HD600/800, and at 11 o'clock with HE-5/5 LE.  With almost all of my headphones I could play the music louder than I would ever want to on the P-1u without clipping or distortion (like with the ZDT), while with the WA6 I could play the HE-5/5 LE at max volume and still fall 4-6 dB below that of the P-1u or ZDT.  The 600 ohm AKG K240M did not present a problem load for the P-1u.  Although I might normally listen with the volume knob closer to 1-2 o'clock, I could turn the volume even higher than I'd like and the amp didn't run out of steam.  It appears that the P-1u has good voltage swing as well as good current handling ability.
 
When listening to live recordings and trying to imagine that I was there at the actual performance, both the P-1u and ZDT offered excellent headroom for dynamic passages, even when the volume was set for higher than normal levels during the quiet parts of the performance.  However, the K1000 needed the P-1u volume to be closer to 3 o'clock, and I could turn the volume to maximum a 5 o'clock with those and it would still not be uncomfortable to listen.  With the K1000 the ZDT seemed to offer an extra 1-2 dB in volume and slightly better bass impact and control, even though the ZDT is also not optimal with the K1000.  Neither amp could give me a satisfactory illusion of "being there" with the K1000 like my SAC KH1000 amp can, and that is not even the best K1000 amp out there.
 

 
SUMMARY:  The Luxman P-1u is a no compromise solid state dynamic headphone amp that is among the best I have ever heard, in my home or at meets.  I don't believe in stereotypes when it comes to headphone amps, such as when it comes to describing SS vs tube sound.  But for others who do, I'll tell you that the P-1u doesn't sound "solid state" at all, if by solid state one thinks of stiff or brittle, harsh, digital, lifeless or cold. But it does have all the speed, linearity, detail and power one would expect from SS.  And it has the warmth and refined euphonic sound that one would expect from a high end tube amp like my ZDT.
 
With my HD800 the P-1u is very slightly better than my ZDT. The sound signature, detail and soundstage on both amps are almost identical, but the treble in the P-1u is a little bit more natural/sweeter and extended sounding.  I have mentioned elsewhere that my Woo WES could use a little more treble extension in comparison to the KGBH SE that I heard at RMAF; so it was interesting to note that the ZDT and WES have a very similar quality of treble, while the P-1u treble reminds more of what I'd heard with the BHSE.  
 
The improvement from the P-1u is not enough to have me entertain selling the ZDT to buy one; but if I didn't already have the ZDT and was looking for a high-end amplifier I'd be more likely to pick the Luxman over the ZDT for many of the reasons I mentioned above, and not just because of the sound (runs cooler, more flexible inputs, loop-out, etc).  If I had a pair of Fostex horn speakers like Blutarsky, or still needed to drive a Stax transformer for my Stax O2, then I might stick to my original choice with the ZDT.
 
ADDENDUM:  I want to add that I know it's not really a fair comparison to put a $449 DAC/Amp combo like the HDP up against a $3000 dedicated amp, but it was helpful in providing a contrast that enhanced the differences and more easily showed what the P-1u does better than the average SS amp.  And while I like the HDP as a backup or bedroom SS amp, it would never fill the role of the Luxman or ZDT in my main rig.  While the HDP wasn't completely embarrassed by the amps costing 2x as much, the Luxman is superior to it in most areas - especially in soundstage or spaciousness, transparency, neutrality and refinement (plus low volume channel balance).  The biggest area where the P-1u excelled over the maxed WA6 and Amphora was in soundstage size and depth, where these single ended amps normally kept up with my balanced Sq Wave XL in that area.  Additionally, the P-1u also held an advantage in treble extension over the Amphora (ignoring the power differences).