Let me first say that this is my first Yulong product. And while I've used many Chinese products before, Yulong stands out in its own way.
 
  
                  
 
 
The DAC section is wonderful, it just hits exactly where I want it - at least for now, considering my listening preferences (which have a tendency to change). It hits the right notes for me. Going from a warmish DAC like the Audio-gd NFB gave me more joy in the treble department when using the D100. I firmly believe in that the DAC should be as neutral and transparent as possible (colouration should only be picked in an amplifier or change of headphones) but I would rather call its sound more natural than straight up neutral. Not that's it's any less neutral, don't get me wrong on that, I just find that rather than having very crisp highs, this DAC manages a very smooth upper end while maintaining great extension. I felt that some female vocals and cymbals etc. felt a little dry coming from an Audio-gd, and somewhat crisp from an ODAC and ST(X); but with the Yulong D100 the treble especially is very smooth and natural sounding. And even though my perception of this DAC/Amp would be that the highs would make my PRO900 for example unbearable, but not so. Sibilance I don't think you can entirely get rid of unless with some EQ (and I've owned some warm equipment), but the metallic highs can be countered, and the Yulong does well in respect to this. The smooth, yet neutral signature of the DAC--feeding my V200, provided with a very nautral sound through my HD650. And regarding the bass, it is wonderful. It goes deep and hits hard with a great deal of detail. 
 
I would say the Amp section is almost equally as good. In comparison to the V200 the differences are quite subtle. What I noticed most of all is that the amp on the D100 provided a heavier dose of bass, mayhaps less controlled; while the V200 provided a slightly more natural sound with emphasis on vocals, somewhat more organic--so to speak. Soundstage I would say is almost about the same except that the V200 give a tad little more space (this isn't saying that the D100 has a tight soundstage, connect an amplifier that does soundstage well with perhaps a pair of cans that has arier and more open soundscape, and the D100 will expand with the rest of the equipment)
 
The Yulong D100 is one of those products that actually impresses me. I have heard that it should compare to DACs like the Benchmark and Lavry, but since I haven't heard either of those units I cannot make a comment on that part. From what I've heard though, the Benchmark DAC1 can be a bit bright, whereas, at least to my ears, the Yulong D100 MKII is quite smooth and polite in the upper register. If you're after a DAC/Amp with a very good Amp section, hands down the D100 is the product, especially for its humble price tag. It also has a Sound option between SoundMode 1 (which should be the most neutral) and SoundMode 2 (which should be a touch warmer). During the burn in process I noticed a slight difference between the two, but so far I preferred Mode 1 even with my PRO900 on some tracks.
 
Build quality is quite solid, apart from the slight cap in the back upper plate which I presume is there for ventilation's sake; as well as the plasticy volume knob which turns in toggle/clicks, rather a continuous switch, which can be annoying when you want to adjust volume precisely. The input options are plenty, and that's great. The only problem one might have is using USB which supports max 96khz. I have nothing against the design itself, I like its wide dimensions, and I love the display which adjusts KHz depending on the source, but it's a shame that the on/off switch is placed on the rear rather than on the front like say on the D18 and A18. And although it stacks with its big brothers, it's a shame it doesn't share the same colour, eg entirely black or entirely grey.
 
Also note, that if you plan on using the amp section, I believe the best thing would be to mute the sound/volume knob on 0, and unplug/insert headphone while the amp is on. While having the headpones plugged in while powering on/off I noticed a very strange sound, possible a similar thing that occurs with some Schiit amps that affects the drivers in some way. I could be wrong on this, but ever since I noticed it I've been plugging and unplugging while the amp is powered on and muted without any issues.
 
Aside from all else, for $450 this is an absolutely marvelous piece of equipment, whether you'll be using it as a DAC or a DAC/Amp, though I believe its strongest area lies in the DAC section which should yield even better results with a greater amplifier.
 
 
                                                                                 

One of the best headphones for gaming and movies - superb for EDM and dubstep
 
              
 


Source 1: Asus Xonar Essence ST (OPA2170 + JRC2114)
Source 2: Audio-gd NFB-3.32
Cables: Signal Cable Analog II and stock coiled Neutrik 3,6mm
Amplifier 1: Matrix M-Stage (with LM4562)
Amplifier 2: Violectric V200

Music played:
Skrillex, Knife Party, Netsky, Adventure Club, M83, Infected Mushroom
Florence and the Machine
Foster the People
Depeche Mode
Röyksopp
(All the tracks were FLAC/ALAC 16bit 44.1kHz and 48kHz with ~1000kbps)

The Design
The Ultrasone PRO 900 have very robust / sturdy and have a beautiful silvery/metal-like finish to it on the sides of the phones. The general build quality seems very solid and it wouldn't amaze me if this thing could take a lot of beating and survive. They're also a bit heavier than your average headphones, depending on your model of course. Other closed headphones could be a bit heavy, but open cans are generally very light in comparison to these. They're also designed to be portable, probably a really good thing for DJing? You can fold the phones up to the rim and if you have deep pockets they can fit in there, otherwise you have a neat little bag that's included. Changing earpads is also easy peasy, you just rotate/screw them gently to either side and they come right off. Putting new earpads on is just as simple, just press them in where they fit with the bent edges (just like placing a square or a star into one of those boxes for babies) and then rotate them on so they lock.
 
The Comfort
At first wear they feel odd on the head. Since the headband is fairly bendable there's not necessarily much clamping force, but there's a tad more force on the upper areas of the earpads just above the ears. But after a while this is overlooked and the headphones are pretty comfortable, not really that clamping, and the earpads are softer and a bit more comfortable than the ones on the HD650, but still doesn't beat the comfort of the DT990. Overall I would say they're comfortable, more than could be expected. But I should add I have a fairly small head - and I could probably see and issue with people who had bigger heads. Earsize could make an impact as well, but unless you have troll-like massive ears I wouldn't be worried. They're about the size of the DT990. Some people have complained about the padding on the rim which feels uncomfortable on their heads. I can feel it sometimes too, but I won't attribute it to the padding but rather the weight of the headphones - they are fairly heavy, noticably heavier than my HD650 and DT990. Atm I feel quite comfortable with them on. They're not clamping and I don't sweat with them on. However, sometimes the weight can be a little straining and fatiguing; that is my only dislike about the comfort of the PRO900.
 
                        
 
 
Initial impression (Burn-in 1-2h)
The first hour of burn-in the Ultrasones PRO900 was hideous. I tried it first straight through the HP out on my Xonar Essence ST. As soon as I connected my Little Dot MKIII it became much more bearable. The warm tube amp managed to soften the higher end of the headphones and brought extra thump and depth to the bass, but still, the highs were prominent and on some tracks I felt a terrible sibilance that could not go left unnoticed. At this stage I realized that I will need many more hours of burn-in. At this stage I also played a random trailer in HD called 'Sorcerer and the White Snake'. I'm a huge film buff, but this trailer seemed like a total piece of laughable garbage. But nontheless I was captivated by the sound the PRO900 managed to present that I disregarded the cheesy CGI effects of the movie. The bass was brilliant: deep and detailed, the highs in this case worked well in the trailer and I can see the V-shape working quite good in movies and possibly even games. The soundstage also felt deep, but not necessarily very wide. I wouldn't call it bad, it's good. But going from the DT990s I felt something odd, I think it could be because of 2 things: the intruding bass, and the fact that the headphones are closed designed - but nontheless there was a good soundstage despite it not being very airy/open (I suspect it is the S-Logic in the works). I also took the liberty to listen to a few dubstep tracks. Generally I don't listen to this genre much, but I thought I'd bring some of it in when reviewing the PRO900 since they should excel in this type of electronic music. I have to admit they have much more power and thumping bass when comparing to the DT990s. Some tracks however were very heavy on the highs, there was still noticable thumping in the background, but you could definately feel the texture on these tracks, which you could not on the HD650 for example (the bass wasn't even present on the Sennheiser). Skrillex - Alejandro is not that bass heavy track, but there's a beat in it that I dig, and it was really present and deep on the PRO900, I remember how I kept tapping my foot to just this track, and even though it was just the first hour of burn in and the highs felt at times pretty sibilant, the PRO900 were very enjoyable with this genre. The DT990s were also bright, but softer and with less bass, at least not as deep and punchy as that of the PRO900. I felt the soundstage was more enjoyable on the Beyers.
~24h Burn-in: The bass has become more pronounced and emphasized. The highs are slightly, just slightly more defined but still quite sibilant at times. It's less dry, but only by a margin. I believe I will have to wait longer for the final burn-in process to finish. I'm estimating around 100+ hours judging by the other members.
 
Burn-in after 24h
The bass seems to gradually come forth more, and apart from minor detail adjustments I felt more impact from the beats. The highs were a little smoother, but just a little. I can imagine I would need a lot more time to burn these in, I'm expecting around 300 hours considering what other people have said.
Conclusion: If possible, I would recommend a warm amplifier - but since it's a low impedance headphone you would mostly be restricted to solid state amplifiers, unless you have the money to go for a tube amplifier with an output transformer - or possible a hybrid amp like LD1+ if you find it good sounding. Having a warm source might help also, but only marginally - however I can imagine either the Yulong D18 or Rega DAC having some impact with their rather analogue sound (I have not tried these DACs so my I'm only speculating).
My gear consisted of rather budget-oriented equipment but in good stuff for the buck. I can imagine the Ultrasones sounding even better on more expensive gear. I recommend these headphones for some electronic music (mostly dubstep). But overall I would classify these headphones as great for movies and games, it brings a new dimension to these medias' sound and make them more immersive than is. A little convenience of these cans is that they're portable: either by using the small neat bag, or by just folding them in - just expect to bring them to a place where the equipment is made to drive them properly. But, portability might not always be a convenience with these cans. Maybe if you wish to take them with to a meet or to a friend's. People have reported that the PRO900 work well with the portable Fiio amps. Just because they have low impedance does not make it easy to drive in my opinion. You have to take into consideration 1) output impedance and high damping factor for better bass response and 2) output power. The M-Stage runs at 5ohm output impedance (which is ideal for 40ohm) and 400mw/60ohm. It does quite well for the PRO900 and its slightly warmer signature is a good compliment to the brightness of the Ultrasones. However I can imagine these headphones pair very well with the Violectric V200.
 
Impression after 300h
I let the headphones play for more than two weeks through the M-Stage and normal to high listening volume (listening only 15 minutes each 2-3h interval). I can attest to the marginal difference in sound (without trying to be affected by brain burn-in). The bass feels fuller and it seems as if the low-end has gotten more body than it used to have. The sibilance however is still a big factor in this - making some tracks less listenable to, but it's not as terrible as it used to be. The op-amp change in M-Stage could factor in on this.
 
The Soundstage
Yes.
There is definately a discernable holographic soundstage on these headphones despite them being closed. They aren't as airy as the HD650 or DT990, but they do have a sense of width and depth, still. Some people may call it 'fake' or 'unnatural' and to a certain extent I would agree. The best I can compare this type of soundstage, most likely a bi-product of the S-Logic, is to Dolby Headphone. What it does is that it creates an audible space between the ears and the instruments, making it feel as if the sound is further away from where the drivers actually sit. If you know what Dolby Headphone with Virtual Surround sounds like then you can expect a similar effect from the PRO900. Though its effect is probably just half of what Dolby Headphone produces, which is good news for you who don't like DH. I find this ideal for HD movies and gaming, especially if you have Dolby Headphone enable when using the Ultrasones.

Isolation
This is an important factor to closed headphones, mostly because you don't want any sound leakage for others to hear, but also to help prevent you from being disturbed from outside noise - it also contributes to the bass response, as you may be aware of. When I wear them I barely hear much from my surroundings: I have a mechanical keyboard which can make much noise sometimes, especially when I play games or chat. Playing music while typing is no issue, but I can still hear the keyboard if I stop the music. Also, when people speak I usually have to take off my headphones to hear them clearly. From a 3rd person perspective there was minimal leakage on medium to semi-high volume on bass-heavy tracks.

Bass
This is probably what makes the greatest representation of the PRO900's signature. It's quite deep, very punchy and detailed+controlled. I would say it excels more at mid-bass rather than low-bass. I haven't tried any headphones that do low-bass very well, but I believe the Sony XB-1000 or the XB-700 and the Denons should fit this bill. The bass on these headphones can probably be described best as a built in subwoofer. When the bass hits as deepest (especially with some EQ) on some tracks or movies it literally feels as if the ground is vibrating; as if you have a subwoofer standing on the floor. It's a very interesting sensation, although it's all in your head.
On music the mid-bass shone. It gave so much texture and quality + quantity to dubstep that I could listen to the genre for hours even though it's not really something I prefer listening to. The impatcful and quick punches worked really well with the treble on most electronic songs (but mostly just dubstep, it don't work so well with most Röyksopp tracks). The sub-bass was also quite good. For example, 'Knife Party - Sleaze ft. Mistajam' was head-shaking and punchy on the PRO900. However, do enjoy this type of mid-bass at its fullest the tracks got to be emphasizing this frequency, I found most of the tracks from Knife Party and Infected Mushrom do this well.

Highs
Another part of the signature, contributing to the V-curve in its frequency chart. Think of it like this: the highs are just as prominent and exaggerated as the bass on these cans. Whether it's a good thing or a bad thing is up to you. Personally I think it's more straight forward and engaging, but it's gone way further than the DT990 - even to the point where you could hear sibilance depending on what song you listen to. Burn-in helps soften the initial peak, but it won't go much further down. Luckily, it does go down after burn-in, unlike the bass which seems to go up after burn-in. Listening to Fleetwood Mac was not a very nice feeling. It was overly bright most of the time, and when the cymbals struck it was really high and screechy. To sum it up, on dubstep and most electronic music I ended up raising the volume for more bass thumping; but on pop and folksong I had to lower the volume due to its excessive amount of sibilance. Röyksopp was a mixed bag. I absolutely loved how the Ultrasones performed on 'The Girl and the Robot' for example, but on other tracks the highs were too umbearable. Same goes for 'Florence and the Machine - All This and Heaven Too' where sibilance was very noticable on the many 'sss'es ontop of it being a female vocalist. Same goes for the cymbals and drumkicks in 'Foster the People - Waste'. Short answer: depending on the source it can become very fatiguing at times, and rather than tapping your foot to the rythm you oftentimes end up taking the headphones off for a break. 'Susumu Hirasawa - Yume no Shima Shinen Kouen' however was by far the worst track for these cans. It was so bad that I felt like pressing two screwdrivers into my ears just to remedy the damage done to my head. These headphones need very specific music! You have neutral cans, you have allrounders, and you have basshead cans, THEN you have the Ultrasones.

The Sibilance and its Sensitivity
This is the inconvenience of these headphones. Due to its bump in the higher frequencies the sound can be very sibilant depending on the recording. Florence and the Machine did absolutely not work on the PRO900. Florence has such a bright and loud voice which I love, but on the PRO900 it is something that I hate. The PRO900 is also quite unforgiving of low quality recordings and quickly points out the flaws of your tracks. This could be attributed partly to sibilance but also its sensitivity. I still have some 128kbps to 256kbps songs and the Ultrasone did pronounce how low of quality they are, and it can be very unforgiving. Through the V200, which is generally very silent, the PRO900 made a little noise audible at max volume without extra gain setting. And while listening to some orchestral tracks in FLAC/800kpbs, I noticed some background noise of the instruments and recording room which I had never heard before. May this be a good or bad thing, in any case I wouldn't recommend them with classical and orchestral tracks.

Midrange
Not a strong point of the PRO900 as the mids are very recessed, even more so than on the DT990. And consequently it makes some genres of music quite unbearable to listen to, especially Susumu Hirasawa, Fleetwood Mac, Florence and the Machine or Depeche Mode; that is when my HD650 shines. In comparison PRO900 sound hollow.

Amplifier
I think an amplifier in general is important overall for hi-fi headphones, but more so for Ultrasone PRO900. I tried three different amps in this case, gradually stepping one in the price range and quality and sound signature. The first contender was the built-in headphone amplifier in Asus Xonar Essence ST which runs at around 11ohm output impedance and can drive headphones up to 600ohm - it did a good job driving my DT990. But how does it go up with PRO900? So-so. The most think that I found was lacking was the bass, the treble was too overwhelming. Of course I could counter this somewhat with some equilizing - but without damping factor in motion I could hardly get to the PRO900s true signature - and the treble still peaked the bass on bass-heavy tracks. As soon as I switched to the Matrix M-Stage everything seemed so much better! The ouput impedance is at 5ohm on the M-Stage which is a perfect suit for the 40ohm on the Ultrasones - plus the LM4562 op-amp added a warm coloration over the stock op-amp that went really great with countering the treble-peak of the Ultrasones; it also added a thin extra layer of bass quantity. And this time I felt that the bass was more emphasized than the highs but not only that... they felt fuller now and powerful and not as thin and metallic as they did through the sound card. In my opinion the M-Stage is a perfect match for these cans at this price range. Now, can the Ultrasone PRO900 get any better? These are things that I've heard, but since I no longer own the Burson HA-160 I could not try it out. Although, I have tried it on the V200 and found that its grainy treble was 'tamed' by the smoothness of the Violectric. However, the treble will always be there (maybe less sibilant on greater/coloured amplifiers), but not so much if you compare its use on cheaper amps. I don't honestly think it's a true musical or detailed/analytical audiophile headphone, but it's still very fun (maybe hateful and unforgiving sometimes) and very engaging. Other amplifiers I do believe work well with the PRO900 are Burson HA-160 and Yulong Sabre A18 since they share similar character as the V200, but maybe even more so, at least the Burson HA-160.
 

In other areas

Gaming
Brilliant headphones for FPS gaming, I'd say. Battlefield 3, Counter Strike, Metro2033, Skyrim felt much more immersive and engaging. Especially with its S-Logic holographic soundstage and deep lively bass. Explosions never felt more powerful and real when shooting from a tank or having a grenade explode some yards away from you. And the shouts never felt as overwhelming and authoritive in Skyrim as with the PRO900 (especially in the intro theme: you can literally feel the choir reverberate in your head). And in this case I really think the V-curve sound of these headphones work really well! It might just be my personal preference but I would generally prefer games to emphasize the highs first and low-end to mid bass. Bass would attribute to the more immersive sound of explosions and gunshots for example, while the highs apply to voices and detail to footsteps etc. I have used my HD650 when gaming as well and felt them less engaging and alive than my PRO900 simply because of its emphasize on midrage and weaker bass. Of course they feel slightly more airy/spacious as they are of open design, but other than that I don't feel the same vibe in games I get with the PRO900. The only issue I had with these cans in gaming were possibly in games like Crysis. Because of the extreme highs the voices over the radio were very shrill and annoying. I also mentioned that explosions and shouts seemed very powerful - to a degree it is true, but the gunshots were more prominent as these cans emphasize mid-bass. For more rumble I'd suggest a pair of cans that has deeper bass extension and does low-bass really well. The PRO900 does it well in fact, but its strength lies in mid-bass.

Movies
Ultrasones went really well with movies, especially with the action genre (and its many sub-genres) as it presented a very lively and powerful bass and this semi-artificial soundstage. It sometimes felt as if I was sitting in a room with speakers and a powerful subwoofer pumping on the floor. Similar sensation can be achieved with Dolby Headphone, but I found the Ultrasones working just fine without any DSP. I should also add that when comparing the Ultrasones PRO 900 to the DT990 600ohm in movies (where I would say the DT990 won in terms on soundstage), there was an interesting finding that I made in one scene of the film 'Tower Heist'. It's an indoors scene and you can hear a car drive by outside rather faintly. On the DT990 there was nothing unusual, sounded just as a car should. But on the PRO900, on the other hand, it sounded rather unnatural and impactful; imagine watching 'Transformers' or something with exaggerated electronic/robotic sound with a plentiful amount of raised bass - that's what it sounded like, as if the car's movement affected the door/walls of the building making them 'vibrate'. I kind of like this effect when watching films, but might not be suited for those who want a more natural film watching experience. Of course, I would resort to my HD650 when watching more serious films; the PRO900 will be reserved for shows or commercial (mostly action-packed) movies. The film genre must be very specific when choosing to use the PRO900 respectively the HD650.
 
Conclusion
If possible, I would recommend a warm amplifier - but since it's a low impedance headphone you would mostly be restricted to solid state amplifiers, unless you have the money to go for a tube amplifier with an output transformer - or possible a hybrid amp like LD1+ if you find it good sounding. Having a warm source might help also, but only marginally - however I can imagine either the Yulong D18 or Rega DAC having some impact with their rather analogue sound (I have not tried these DACs so my I'm only speculating). The V200 is quite warm sounding, but with detailed highs, perhaps not as emphasized with rolled off highs as perhaps a Burson HA-160, but a good pairing with the PRO900. It smoothes the excessive treble peak and refines the sound even more - especially in the bass department as it bolsters a great bass extension.

I can recommend these headphones for some electronic music (mostly dubstep). But overall I would classify these headphones as great for movies and games, it brings a new dimension to these medias' sound and make them more immersive than is. A little convenience of these cans is that they're portable: either by using the small neat bag, or by just folding them in - just expect to bring them to a place where the equipment is made to drive them properly. But, portability might not always be a convenience with these cans. Maybe if you wish to take them with to a meet or to a friend's. People have reported that the PRO900 work well with the portable Fiio amps. They're not hard to drive, but I can imagine you'd want a considerably altered sound in your amp when using these ultra-bright, ultra-bassy headphones. I switch between both my HD650 and PRO900 from time to time but generally it looks like this, usagewise: Music + Films (less intense and more acting, scenic) for my HD650, and Games + Films (intense, action-packed) for my PRO900 (with perhaps the exception for EDM and dubstep when listening to Music). These two headphones are so dynamic in that they have so many differences in both strengths and weaknesses that sometimes I would recommend people to own at least 2 pairs of headphones - instead of focusing on just one pair as allrounders for all your sound oriented activity. Even if music is your primary (or only) activity then one type of headphone could perhaps not be enough unless we're speaking expensive orthodynamics and you're on a tight budget already. Think of whatever activity you value the most, or what music genre you listen to the most. If you listen to a lot of EDM, Dubstep, etc. then the Ultrasone PRO 900 is one of the best headphones for this kind of listening - they offer that umph that headphones like HD650 lack (or open headphones in general) and yes even the DT990s. Don't get me wrong, I loved the DT990s, but the electronic music I felt they worked well with felt quite restricting, tracks that the PRO900 nailed it in felt less intense and engaging on the DT990.

 

Little Dot the title can be telling in many different ways - I read one head-fier refer it as a small and unimportant smear (when comparing to the Darkvoice). But in this case the Little would be how much you'd pay for something, but in return you get more than you could have bargained for. Here's why:
 
If you've considered to try out tube amps then the LDMKIII could be either a good or not so good start for different reasons. If you're after considerable warmth and alteration of sound toward the darker side then the LDMKIII can supply you with that, but only to some extent - this amplifier is not all about warmth but also detail. If you're going from a transparent or clinical sounding amplifier then you'll definately hear the difference. It certainly makes the mids more smooth and the bass hit just slightly deeper. But rather than smoke and fire - I would define its warmth as cozy ember, it's not overly aggresive and alterating, but you feel its presence; and in a good way. However, it is not only nice in the midrange it extends and smoothes the treble a little bit. If you've decided to pair the DT990 with the LDMKIII then definately look into tube rolling (stock tubes rarely sound good in any case). With the Voskhod tubes it made the highs on the DT990 slightly more bearable in that they felt smoother, while they were considerably less promiment with the Mullard M8100. At the moment I have my HD650s paired with the LDMKIII and the Audio-gd NFB-3 (all of which are considered to be 'warm') and still what I feel I get most out of the LDMKIII in the system is detail - you could almost say its leaning toward the transparent side for being a tube amplifier - even with the warm tubes like M8100. Whatever I listen to the bass is never muddy or bloated, and the mids are not smeared in any way - there is considerable clarity and detail, and some of it is thanks to the treble extension. Its 'warmth' is not overpowering... it's there, as a companion to the clear detail and soundstage that this device furnaces. And if that is what you want from your amplifier then the Little Dot is a great choice. However, I have read that compared to some other tube amps in its price range it has less tube rolling options (might have changed in the years), nontheless you have options and quite a few of them - all offering different things and not just slight differences.
 
For me it's hard to comment on the design - I generally liked it and prefered it to other tube amps. But it might not rock everyone's boat (it shares similar shape as the other post MKII products, ie the half-cylindrical shape).
 
Build quality can be argued over as well. I've read that some people had some faulty ones shipped to them. In my case I haven't had much trouble except that the back AC connect is a little loose (not that it's on the verge of falling off because it won't, it's just not entirely 'plastered' there, you know) it's not something that is an error in just my device but a general build issue - no biggie. Other than that the tubes run very hot - speaking of the power tubes that can run to 120 degrees according to the user's manual. And in turn the entire device runs quite warm - even the case is fairly warm to touch. I don't see its heat problem as a big issue unless you live in a really hot place and have little ventilation. Tubes do run hot in general, but for its size I would think that the LDMKIII is a tad warmer than it should be. Lastly, some have reported that they have heard interference noise that the Little Dot picked up from their phones. I had only one case of this happening to me and it was just slight and quite brief (mobile phone in pocket) - but it actually happening does prove true to others' finding and perhaps not something you would find ideal in an amplifier, even if it's budget oriented.
 
Generally I would recommend this amplifier on the condition that you change the tubes for something more approriate and better sounding. And again, the sound on this device is pleasent sounding and full of detail. It might even bring out flaws in your source - cause it did in some of my tracks which unfortunately are around 192kbps and 128kbps until I buy and rip the CD quality of just these hard-to-get tracks. With my FLAC files on 900-1200kpbs the LDMKIII really brings out a new layer of sound without any terrible distortion. And while it brings warmth to the table it's not necessarily dark, deep and powerful, but smooth, sweet and mellow - which I think complements the HD650 well if you feel that you could use just a little bit more warmer tones to your tunes.
 
Also note that some users have found distinct differences in sound signature when switching between the gain setting on this device. To my personal liking I prefer the gain 10x and 5x over the 4x and 3x. But depending on your taste it might be different - it just requires experimenting, just like the tubes.
 
I've run both Beyerdynamic DT990 600ohm and Sennheiser HD650 through the Little Dot MKIII and found it to work well with both - of course with different tubes to alter the sound in different ways.

I picked up the Beyerdynamics as my second real hi-fi phones to replace my Sennheisers HD598 in order to get something bassy, yet with an open construction. While they were a huge improvement to my previous phones, they did not reach my expectation in the bass department, and I will explain why later on.
 

 

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Treble: First off I should mention the initial sound signature of these headphones. They're very bright! You might have read about its treble, and it is true, they are truly trebly phones. But the treble is not at all what some people exaggerate it to be. Yes, the treble is noticable, and is perhaps the first thing that will strike you when you first listen to them. But the treble is detailed and deep and not sibilant, and it serves really well with some pop tracks and electronic music. The treble is also very engaging, it brings life into the highs and brings out the cymbals, but they also made female voices stand out before the instruments, as well, which is a positive thing when listening to pop.
 
Soundstage: It's wide, and great! As these phones are open, you might expect them to perform well in the soundstage department. With the wide soundstage of the DT990s the treble does not strike too close and too engaing to your ears. They're at a distance, but well detailed and refined. Making them even more ideal for electronic music. For electronic music I chose Susumu Hirasawa, where soundstage can make an impactful role. On some tracks the voice is supposed to go as an echo among the instruments in a distance. Though it is a male voice it becomes slightly more apparent than the high tone instrumental tunes, and it creates a life-like sound stage with a good separation of instruments on some of the tracks from Fleetwood Mac - which in comparison does a better job on the DT990 than the HD650, which is more close-sounding than the Beyers, but with less prominent highs. But again, sometimes the male vocals are less prominent and less refined, making it sometimes overwhelmed by the other instruments. Of course, this was quite rare with Susumu Hirasawa as his voice is generally fairly bright on most tracks. But it did not work well for me on male vocals in operas and some orchestral music.
 
Bass: Yes, they have bass, which many other head-fiers and pointed out. But some may exaggerate a bit here as well as with the treble. For an open construction these cans have some bass that amounts for quite a bit, but it is also detailed and far from muddy or overwhelming. It's fast-paced and you will notice some punch to it on some tracks, especially to some dupstep tracks--but know that these cans are not exactly ideal for Dupstep or Hip Hop. They are generally bright cans, and while they do have a fast and detailed bass, it is not in the spectrum of being plentiful enough to be considered "Bassphones." However, to some tracks the bass is quite noticable and manages well with emphasizing the lower frequencies: such as the beginning of Massive Attack - Angel, as well as the punchiness of Morgan Page - In the Air.
 
More importantly: If you listen to some bass-heavy tracks, such as the start of Morgans Page "In the Air" (especially if you are using any equalizer to enhance the lower frequencies) then at a certain volume level one or both of the drivers will rustle. At first I thought I had a faulty product, but investigating on the forums led me to several other cases where people suffered from rustle on bassy tracks with high volume. Amplification might help in this case, and you might be able to raise the bar of the volume level before reaching the rustle, but only slightly if so.
 
Comfort and Design: This, alongside the soundstage, is my favorite thing about these cans. When I first took them out they looked really robust and uncomfortable. But as soon as I took them up I realized how light they were and how extremely soft and comfortable the earpads on the thing were. Taking them on was a breeze, and the headband padding was also very comfortable - it felt as if you weren't wearing anything on your head! Again, the design, as mentioned before, looks very robust and industrial; especially how the cables go slightly bent/rounded above the earpads - and this sort of design does signify just what type of sound signature you might expect: bright and detailed with a wide soundstage (the width of the earpads). To me, the design does not necessarily strike as a pair of bassy headphones, and to some extent that is true, but it still does have a slightly more impactful bass compared to the HD598 and the HD650; but it is often associated with the treble, making drumkicks and such sound brisk and bright but still quite punchy.
 
Comparison: I'm not even going to compare it to the HD598, the bass, detail and comfort is far more superior on the DT990s. But I could compare it to other phones in proximity of its price-range and sound signature; and of course, with headphones that I have tested out and own(ed). To the HD650, I prefer the DT990 on most electronic music without vocals (or female vocals if included), for the electronic music I prefer to listen to the male vocal is slightly brighter than most other male vocals, making this artist more ideal for the Beyers. The DT990 was also way more engaging and more open than the HD650. I love the HD650s equally as much, but for electronic music, pop, and some classical music I preferred the DT990 where the soundstage made more impact in addition to the well prominent and detailed highs, making electronic music feel electronic. The Sennheisers are more musical/warm, and are less engaging and bear less emphasis on the highs than the Beyers, but I did feel more bass quantity on the HD650 on some tracks. However, I did feel slightly more detail on the DT990, while the HD650 were a little bit more muddy in comparison to dupstep and songs like Massive Attack - Angel and Morgan Page - In the Air.
 
As for the Ultrasone Pro 900, the DT990 600Ohm is quite similar in terms of sound, but some areas should be considered to be very differentiating. For example the bass on the Ultrasones is ALOT better in both quantity and quality - but the highs are far too bright on the Ultrasones and softer on the DT990s. Also the soundstage felt more natural on the DT990s - most likely cause the Beyers are open, and the Ultrasones are closed. To my ears, the Ultrasones had wider soundstage but it was unnatural in comparison to the Beyers - this could be due to the holographic S-Logic of the Ultrasones.
 
Conclusion: For the price range, the DT990 600Ohm comes with a lot of value - especially for movies and games. But the rustling drivers, the slightly recessed mids, and the high amount of treble are things to consider before purchasing these cans. In all honesty, despite its cons, these are really quite pleasent headphones to have - if you can get them cheaply. And they work even better with OTL tube amps. When I paired them to the LDMKIII with the Voshkod tubes, some of the 'harshness' was reduced. Or rather, the treble felt less protruding, but the clearness and the detail of the highs was still intact. If you're listening to electronic music and pop, then I can warmly recommend these headphones.