You've already heard that the sound quality of this amp does not match its (low) asking price. You already know that it's one of the best SS desktop headphone amps you can get for your cans at any price point, really. So why am I writing another review on an amp that you KNOW is going to be awesome? Well, my review is for those who like to build their own amps and JDS labs is a company that "gets" the DIY movement and have made NwAvGuy's design really easy to build for those of us who like to roll our own gear. My review is meant for those who might be interested in ordering a DIY kit but who might not be sure of what they're going to get:
 
Remember back in the day with the O2 was new and there were people scrambling to put together Group Buys for PBCs and components? Well, those days are OVER, thanks to JDS Labs!
 
All the components come in their own plastic baggies, labeled clearly so you know where they go on the PCB. The PCB itself is of the highest quality you can expect as are the components themselves. All op amps and mosfets come in sealed anti static bags. For me, this kind of kit is a dream - I don't have a lot of time (or patience) to wait for people to put together Group Buys for an amp like this to save a few bucks. You would think that JDS labs would be marking up the cost of the DIY kit for this convenience, but frankly, they deserve a lot of credit for being able to provide the DIY kit for this amp for almost as much as it would cost you to go and buy the parts at a local electronics store, so the small "up charge" that you're going to pay isn't much at all when you consider how much time you're saving if you were to decide to spend a few days gathering the components yourself (and it might actually cost you more considering shipping charges and/or gas).
 
I built mine using Cardas quad eutectic solder (the ones JDS sells are built using lead-free solder). I'm sure lead-free solder is fine, it's just my own personal preference to use quad eutectic solder for all my builds (and that's the nice thing, isn't it? You can use whatever solder or equivalent components of your choice for builds like these if the ones included aren't to your liking). It took me about 3.5 hours to put together the kit (PCB board and components, $60 at the time of this review). 
 
At the time of this writing, there are no detailed instructions on how to put the kit together yourself on JDS Labs' website, but you don't need any really. Everything is labeled on the PCB itself, and everything is separated and labeled in baggies for you. There is however, help on their site for the various mods you can do (gain, RCA connectors, rear power, etc.) You do need to know how to install components for a build like this (like knowing which is the positive lead on a capacitor and which is pin 1 on an op amp, etc.) Adequate soldering skills are also necessary and I highly recommend a variable control soldering station for this kind of build too.
 
JDS Labs' customer service is excellent. I've received responses to emails within a short amount of time and I've got nothing but great vibes from them with each response. Although I didn't have any questions concerning the build itself, they have been very responsive and helpful. I ordered an enclosure from them which I later decided to get laser engraved and they've been very helpful in answering file format questions, I'm sure if you have any issues with their kits that they'll be just as helpful.
 
I'm so happy with my kit and interactions with JDS Labs over this Objective 2 that I'm going to be ordering more kits to build soon!

Focusrite may not be a familiar name in the Headphone Audiophile community. Many might be more familiar with Creative Labs, Turtle Beach, ASUS, etc. as makers of "entry level" headphone gear, but for those who don't know, Focusrite is a very familiar name in Professional Audio. Focusrite's claim to fame comes from their microphone preamps, which for decades have been found in many commercial recording studios.
 
Why does this matter to the average Headphone Audiophile? Well, for starters they have experience in Pro Audio and understand that having a good DAC is essential to making critical decisions while working on audio, and so they put a Cirrus Logic 4272 chip in this unit (this is the same chip used on other portable pro audio boxes made by Avid, Apogee, etc.) They also designed this box to be used on-the-go, so a decent headphone amplifier would be important, as many musicians track and mix their songs with headphones. The 4272 chip is well-designed, low cost and does ADC/DAC simultaneously. In my opinion, the unit is worth the cost for just the quality of recordings you can get from it; in addition to the good ADC/DAC chip, you have two excellent, recording studio quality microphone and line preamps (your recordings are likely to sound better than using anything made by the other manufacturers that don't have a pro audio pedigree). The box features low-latency monitoring so you are able to monitor your recordings without having the signal go through your computer's processor first, which would add a lot more delay to the monitored signal; in essence, it is a very decent recording solution for those who might want to record analog sources and convert them to digital formats on-the-go. This all benefits the Headphone Audiophile, who would value having a box with a good DAC chip and clean headphone stage.
 
How does it perform as a portable DAC and Headphone amp? Well, as someone who primarily listens to high resolution audio through a mastering-grade DAC, here are some of my real world observations on this unit:
 
Installation was a breeze. I have read many negative comments online regarding their drivers, but these tend to go back to 2012 when the unit was initially released. Two years later, I can only assume that they fixed a lot of those issues because I had no problems downloading and installing the current drivers on a Win7 Lenovo laptop that I use with the unit. Once the drivers were installed, I set the Scarlet as the default audio device and then plugged it into a USB port using the included cable, immediately a green light went on the unit.
 
As a DAC, I found the quality to be very clean. I've got tons of listening experience with various DACs, ranging from bad to good and a lot of the good qualities I'm used to from good DACs are found here. No noise, a wide sound stage; the DAC is very accurate. The only negative here is that the unit's sample rate tops at 96kHz, which is fine for most audiophiles but it's interesting since the Cirrus Logic chip used here supports up to 192kHz sampling rate (perhaps it's a limitation on this box due to the unit being USB-powered). The 1/4" analog output stage of this box is also very clean and I also use the scarlet's analog outputs to connect to my HiFi receiver whenever I want to play music from my cloud over my home HiFi system, and it sounds great. Here are my comments on the headphone amp alone (which unfortunately isn't as amazing as everything else on this box):
 
I played back some audio from the cloud (Google music library) and listened to the following IEMs/Headphones: Samsung Galaxy 5 earbuds (which are very good for OEM earbuds), Klipsch S4A, Grado SR80i, and my Beyerdynamic DT770 Pro (80 ohms). The headphone amp is able to drive the IEMs without any problems, and it handled the Grados really well (although I found the quality to be a bit grainy as I pushed the level up a bit higher than my normal listening levels). I was able to drive my Beyer 770s fine as well, but again, the sound was a bit grainy as I pushed the levels up past a nominal level; with higher quality amps, you usually hear a well-defined, non-distorted signal (that simply becomes too loud to handle). It seems the headphone amp in the unit is clean, but past nominal levels with low impedance headphones and IEMs, the quality starts to suffer; the audio starts to distort a bit (I didn't even bother trying my Sennheiser 650s on it).
 
I don't think that this box beats a dedicated high-end DAC + Headphone Amp combo, but for about $150, this can be a good purchase for those who also want a portable, very decent quality recording solution on top of having a good DAC and clean (although a bit underpowered) headphone amp to drive low impedance cans on-the-go.

When I first got my HD650s about 5 years ago, I have to be honest and say I wasn't thrilled. Listening to them over my DAC for the first time gave me a bad first impression. I purposely loaded my vinyl transfer of The Police's "Every Breath You Take" because it has a good balance of punch and snappy low, mid and high frequencies (again, I'm talking about my vinyl transfer, not the Remastered for CD version).
 
I was unimpressed by the lack of "WOW Factor" that I had heard from other users/reviewers. My DAC is a high-end Crane Song Avocet which has a very good solid state headphone amp built in. I then read about how these need a few hours of burn-in time, a concept that I wasn't sure was true, as other headphones I own have sounded the way they do out of the box; this was the first headphone purchase I made where burning in was a factor.
 
Skeptical about this phenomenon, I decided to run pink noise while at work for two weeks straight, without listening to music during the entire burning period. After the two week burn-in period, I listened to the same song again and this time there was a noticeable difference in how wide the stereo image sounded. The low frequencies sounded more extended, but I still felt the mids and highs (especially the high frequencies) were just not as present as I've heard them on some of my other cans (Grado SR80s, Sony V6s, AKG 240DF). The other headphones don't reproduce the low frequencies as good as the 650s, so for a while I wrote them off as having a general weakness in the mids/highs.
 
Over the next few months, I listened to all kinds of music with them and slowly began hearing about the "foam mod" and wondered if it would make a difference. I didn't want to risk damaging them, as the smaller foam disc inside each of the drivers doesn't seem like it can go back as it's sandwiched between two layers of plastic that cover each of the drivers. I decided to do this modification, because frankly, I wasn't listening to the 650s as much as I wanted to. After removing the small piece of foam from each of the drivers, I immediately noticed an improvement in the lows and mids; the lows had less "mud" and I was able to hear more detail in things like snare drums and hi hats. The next modification was the cable, and I decided to build one using the Cardas plugs, Canare Mini Star Quad and terminate it to a 1/8" Canare plug. Being able to remove the stock plug easily through the connectors gave me the ability to see if a cable upgrade really does make a difference, and it sure does! I gave up the flexibility of the stock cable, because the heavier cable is shorter and less friendly to moving around, but I noticed immediately that the sound stage improved a bit and I started being able to pick apart elements of the audio in ways I wasn't able to before.
 
The only thing I still wasn't satisfied about after the foam mod and cable upgrade was the high frequencies, until I listened to these through the Schiit Valhalla. I think the tubes on the Valhalla somehow have improved the upper frequencies on these headphones. When I listen to my Grado SR80s through the Valhalla, they almost sound too bright, so maybe the amp (and stock Schiit tubes) bump up the higher frequencies, it seems like it to me, and I think this bump works extremely well for the HD650s!
 
It took me a few years to find a combination that has transformed these into a beautiful listening experience; out of the box, they simply don't perform to their fullest potential (they definitely are picky when it comes to an amp, and I would try them on a valve amp as opposed to a SS amp for the full experience!) I bet many Tube amp enthusiasts are having a blast with these and rolling tubes! I'm honestly perfectly happy now with these and the Valhalla.

I have this and the dedicated DAC/Monitor Controller from Crane Song, the Avocet. The HEDD and Avocet (most recent models) have the same DAC. These converters are used by some of the leading Mastering engineers in the world for their neutrality. At this level, choosing another DAC would simply be a matter of preference; speaking from an audio engineer's perspective these converters are as accurate as it gets (we don't use words like "better" for high-end conversion).
 
Now, why would audiophiles be interested in this ADC/DAC? Well, if you like the sound of Tubes and Analog Tape, keep reading...
 
Dave Hill, the mastermind behind this box created a proprietary set of DSP processes in this box that emulates the sound of tubes (Pentode/Triode) and analog tape. In Audio Mastering, these processes are used to give digital recordings that might sound a little lifeless more coloration. The Tape process emulates the sound of an analog mastering deck in a way that sounds like the real thing, and not found on any digital effects plug-in, and the same goes for the tube processes. It is capable of adding harmonic distortion that isn't in the original recordings, and it can go from subtle (like the harmonic distortion you would hear on a Pink Floyd record) to "crunchy" (like the distortion you would hear on early Motown stuff).
 
I would imagine that any audiophile with a serious Solid State playback system could make their rig sound like they've got several high end Tube amps (because you can adjust the Pentode and Triode processes to your heart's desire) and a 1/2" analog mastering deck (without tape hiss, the process is intended to emulate the dynamic range compression effect of recording to a high-end analog deck). A lot of the albums that are mastered (I'm talking about the high-fidelity ones here, not the super distorted crap that pollutes most of our airwaves) have been done using this ADC and it's been proven to give that elusive "analog tape and tube" sound that was heard on recordings from the good ol' days, that said, the effects can also be very subtle or completely bypassable if you just want to accurate conversion. This ADC/DAC is very well known to the best engineers in the audio industry, how that would apply to an audiophile's living room or den is left to the imagination and taste of the user.
 
I currently don't have enough time to do this for my own personal enjoyment, but I've been transferring some of my older CDs (early generation CDs that sounded "cold" because the converters at the time weren't top notch) and have been processing them through the HEDD to give them more coloration at varying degrees depending on the album. Not only is the result "warmer" than the original CD, but the quality of the HEDD's harmonic distortion is often able to give the transfers more depth that I haven't been able to achieve using other digital processing effects.
 
I know for sure I won't be upgrading my ADC in the foreseeable future! I just wish I had more spare time to use this box for my own personal enjoyment (currently, 90% of its use is for Audio Mastering projects and it's one of the tools in my arsenal that I consider essential).

I had been looking for an amplifier for my Sennheiser HD650 headphones and tried many amps that cost much more than the Valhalla over the last 6 or so years. It's almost like they designed this amplifier to bring out the best of this particular headphone. If you are also a 650 owner and have always thought that they are a bit "veiled" in the mids/highs, and like me have done the mods (foam, cable) and you still feel that after all that's been done that the 650's still sound a bit "dark", then do yourself a favor and check this amplifier out. Seriously, before they realize they can be charging a bit more for it.
 
I had started my quest for the perfect amp for my 650s with Solid State designs, and before the Valhalla, it was paired with the (awesome) Headphone amp on my Crane Song DAC; we're talking about a mastering-grade DAC and monitor controller here folks, and it costs nearly three grand. I still felt that the mids and highs were a bit scooped. A fellow audio engineer suggested I try tube amps. I have heard some very good (and very expensive) tube amps with the 650s and a lot of them (interestingly, most of the really expensive ones) colored the sound a bit too much for my taste. I love the neutrality of the low end that I get from my SS amp, and all of the (really expensive) tube amps I tried colored the sound so much (and then I remembered that we audio engineers understand that if we want neutrality from amplifiers, that Solid State is the way to go). I decided to end my quest realizing that I already have a high-end SS amp in my Crane Song DAC, and simply felt that the 650s could not sound any more neutral and wrote the 650s off as a pair of headphones that simply could not be linear, as tube amps had let me down in the sense that they aren't neutral and colored the sound a bit too much to use in a critical listening situation (most audiophiles are fine with this because coloration is more accepted for leisure listening than it is for critical audio work, where neutrality is most desired).
 
I found out about Schiit and the Valhalla amp a few months ago, and several reviewers said that it sounded neutral for a tube amp, and this is what honestly got me interested. Again, a large portion of the audiophile community may not want this, and I've already seen reviews/comments from people who say to try different tubes because the amp isn't colorful enough. This got me even MORE interested. I got my amp about a month ago and all I have to say is: WOW. The sound stage is amazing. I'm hearing more details in the mids and highs that I had not heard from my 650s, all for under 400 bucks. Obviously I'm not interested in more coloration and love that Schiit offers a full set of replacement (matched) tubes for $40! I could not wish for a better tube amp for my 650s. I have absolutely zero interest in searching for matched NOS tubes, especially knowing that there will never be another set that's going to sound the same. I won't have these issues with the matched tubes that Schiit sells for this amp (and if there is a difference, I'm sure it won't be that drastic). I plan on ordering a couple of spare sets to have (I'm not going to wait until the tubes that came with the amp wear out before I order a few sets to have for backup).
 
For the audio engineer that loves the sound of the 650s but wants a more linear sound from this model headphone, this amp is a dream (and a steal under $400).