Pre-introduction
So, this is going to be a more, let's say, “specifically special” review. I'm relatively new to Hi-Fi gear, but I know a decent amount about audio engineering and production. As I was looking into what headphones I wanted to buy, I found out that was a really tough thing to do. I listen to dubstep, per se, along with the similar glitchy electronica variations. But (I'm going to try and say this as least hipster as I can), I listen to really, really underground dubstep. There's mainstream (brostep like 99% of UKF), the leading underground (like Biome, Mala, Burial, etc) which are very “down low style” dubstep, and then there's the songs that nobody knows and are really only found on Soundcloud and scattered on miscellaneous YouTube pages. That's where I find songs I like. And it's a pain in the ass to find good songs, let me tell you. Before this starts sounding pointless, assuming it already doesn't, the music I listen to combines the “down low” of classy dubstep with the “excitement” of more popular dubstep and does so in a very melodic way. The mids and highs are there to create a feeling and the bass shoves that feeling down your throat. So, when I was looking for headphones, I didn't know what would fit my needs.
 
Introduction
As for the “specific” nature of this review, I will be focusing on the style of dubstep I listen to and how well the headphones suit it. With that, the headphones are adjusted or, rather, tweaked for that reason. I have done Kees' mod, but I only put felt pads on the back wall and on the driver plate (I suppose would be what it's called). I tried it out with the cotton pad, but that just killed everything I liked about the bass. I have about 60 hours of burn in on them so far. It's been said before and I'll say it again, these headphones REALLY need a burn in. After the first day, I was about ready to return them. But even after just 60 hours (most people say 200+ for complete burn in) they have improved incomparably much. I will reserve a post under this review to comment in a couple weeks after the burn in is complete. I will be powering these phones with a FiiO E17 being used as a DAC through USB from my PC. And with all that hub-bub out of the way, I'll get started.
 
Setup
1 week old Ultrasone Pro 900s with approx 60 hours of burn in and the “felt pad” part of Kees' mod.
Fiio E17 being used as a USB DAC + AMP (+12db gain) (35-42 volume) (0 Treble) (+4 Bass).
Foobar2000 with WASAPI and flat EQ.
Songs are 320kbps CBR, 44.1k, 16bit, mp3s.
 

 
Songs being analyzed. (And a little description as to why. I'll go into more detail during the testing)
Vexare – Clockmaker (bass + mid range emphasis)
Hulk – To The Stars remix (low low bass + low vibes + vocals)
Biometrix – Running (bass + wobbly goodness + vocals)
Mitis – Don't Know (bass + huge mid range sounds + extremely complex background sounds)
Mitis – Elevation (progressive style bass + high wobbles that drop into low bass very rapidly)
Mitis – Identity (for being the most beautiful song of all time. And bass)
 
Build quality
These things feel awesome. I wouldn't expect any less from a German manufacturer than to build top quality durability with looks and functionality. They are made of that really good plastic that America, apparently, hasn't yet accepted as being better than metal for such things. The pads are are paddy and stuff (and there's an extra pair). The adjustable-ness of the headband is very solid; it stays where you set it. The removable cable port is strong (which is a really good thing) with no wiggle. So, yeah, they're German. What do you expect?
 

 

 
Comfort
This is kind of tricky. They aren't uncomfortable. But, they aren't very comfortable. Due to the circular nature of the cans, there's not really an area where your ears can be so they aren't touching something. And, due to S-Logic, there's only 1 area your ears CAN be so that you're getting the most out of the technology. So, there's quite a bit of adjusting them over and over and being finicky about how they're sitting. Or maybe, I just have a previously unknown OCD regarding circles and ears, I dunno. But, I can usually get the correct placement and just hold them there. I don't wear my glasses while I'm listening to music, so it's not like I have anything else to do but nod my head, close my eyes, and imagine all the decibels are little warriors of the Trojan war trying to break in to my head. Because my name is Troy.
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SOUND QUALITY
I'll have a mini talk about the different frequency ranges and then I'll have an “overall” summary of them. And then I'll go on to talking about the actual songs I'm testing.
 
Lower Mid Range (150hz – 1000hz)
I like to think of this range as the “perfect sounds” range. These are those dark piano notes that just seem to get you, know what I mean? In any case, this range is very, very important to me. Other than the bass, it's the main part of the song in a lot of the music I have. With the Pro 900s and the E17 (which has a good mid range emphasis), there's just so much detail... so much. Forget anything you've heard about the mids being recessed, I don't know what they were doing wrong. The mid range reaches out and touches you and then falls back into place with graceful pleasure. Piano notes hit strongly and fade away quickly. Wobbles move up and down without any “friction” from interference with frequency change. The range is clear, detailed, quick, and versatile. It stands out from the commotion above it and builds on top of the bass from below it.
 
Upper Mid Range (1000hz – 3000hz)
Normally, these frequencies aren't kept separate from the previous ones, but just keep reading. I'm not going to explain myself while explaining myself. This range marks the end of the “dubstep noises.” Mostly. You don't really see wobbles or heavy frequency modulation sounds past 2khz'ish. And, with filter or pitch LFOs they extend up and down from 3khz to 1khz. The kind of sounds in this range would be the very agitated sounds that old people find disgruntling. But, with the agitated nature of these sounds, they need to have a bit of control. It's more tough to pair bass with the lower mid range, so when there's an emphasis on this range, there's usually some wubwubwub'ing that matches it. Ultrasone must have had me in mind when they made these, because this range has just a little bit of space to it. It's tough to explain, but, along with being incredibly detailed and vibrant, there's also some extra room in there for the bass to come in without disrupting anything.
 
High Range (3khz – infinity and beyond)
Everything past 3khz tend to be the rhythmic bits of the song (hats and claps and snaps and such) and lots of overtones. Overtones errwhere. Upon looking at the frequency response graph for the Pro900s, I got a little worried seeing that they got really happy at 6khz. I don't particularly care for 6khz. We've never liked each other. That said, I don't really notice the spike. I used to notice it, but not anymore. Whether it settled down with the burn in or there's just too much going on below it for me to pay it any attention, I'm not sure. But, the entire high frequency range is relaxingly supportive. “Oh, but Troy, everyone says the highs are super bright and harsh. Get outta town!” (that's how you guys sound to me in my head). Well, yes they are bright. Since the burn in and Kees' mod, they aren't harsh at all, and brightness doesn't have to mean that they stand out over everything. With frequency modulation, there's a lot of importance to overtone quality. I don't want to get really technical here, but if note A at 440hz is a square wave (I love square waves), there's lots of maths and physics going on and it's also producing a note at 1.3khz, 2.2khz, 3.1khz, 3.9khz, 4.8khz, etc. And these are all very important in frequency modulation because you can pick and choose which overtones you want to mess with and do fun things with them. Long story short, the brightness of the Pro900s accents these notes very well. Being overtones, they are paired with lower frequencies, but they don't stand out over them at all. These are sort “side sounds” off of the “real sound” and they are there to add to them in neat ways and that's exactly what they do.
 
Upper Low Range (80hz – 150hz)
I saved the bass for last. This is where the kicks are and some wobbling will occasionally be put in the mix to try and permanently damage your hearing. Other than that, though, this is where the “backbone rhythm” of the song is. Kicks will emphasize a large sub bass coming in along with keeping the rhythm. This range is actually the most boosted part of the phones, as far as the frequency response is concerned. But, here's the thing... there isn't too much of the mid bass. And this is coming from a guy who is a big fan of sub bass. It's actually kind of soft feeling. But impact-full too. Lots of impact with care. It's like a pillow fight with Tempur-Pedics. The bass rolls around really well and noticeable as the size of the bass is awesome. With all the loving care that it boasts, it doesn't intrude on the mid range at all. It stays behind it and plays nice as the backbone that kind of keeps the rest of the song in check.
 
Lower Low Range (20hz – 80hz)
Awwwwww yeahhhhhhhh. Okay. These are not sub-woofer headphones. If you're looking for something that will squeeze your face sideways and be a force of Zeus, the M-Audio Q40s are a nice choice. The Pro900s aren't like that. At first, I wasn't sure what to think about this either. Before these, I was using phones with D2000ish sub bass levels. So, when I popped the Ultrasones on, the first thing I thought was “where's all the damn bass people were talking about?” Oh, it's there. But, it's not a prideful bass. It doesn't want to bully you, it doesn't want to force you to do something you don't like. It wants to help you. Let's see, how can I explain this...? Hmmm... Well, first off, the sub bass part of dubstep is very, very important. There's all the stuffs going on above it creating a song as songs have always been songs. And then, the sub bass comes in and adds a new element or a new sense, if you will. I'll put it this way. Without the sub bass, the rest of the song is playing and creating a feeling or emotion in your mind. With the sub bass, one of your other 4 senses (touch) also comes into play. The song is touching you. Now, both physically and emotionally. Think about that. The short range of frequencies that the sub bass covers has so much meaning to it. With as short as it is, the most needs to be made out of it. We can't just have everything below 60hz being an earthquake. What Ultrasone has done with the bass on the Pro900s is something I have to use metaphors upon metaphors to try and explain. It's a wonderful creation of sound. The depth of the bass is staggering. We all have felt what 30hz feels like, but do you know what 30hz sounds like? It's a deep cry of sadness. The sub bass on the Pro900s has a mind of its own. Don't get me wrong when I said these aren't earthquake sub-woofer headphones, though. There's plenty of push from the sub bass, but it's the sound that's really special. Not just the feel.
 
All the Elements Combined
With all this commotion, you would imagine it may just be too much. And that would make sense. If these weren't engineered by the Germans, that probably would be the case. I think the REAL final piece of these phones is S-Logic. I really do. And you can easily tell by moving the headphones around (or just flip them). As you move them forward, the bass starts to muddy up with itself and the treble and mid range go into hiding. If you move them backward, you're just going to have more treble than you know what to do with and there will be no bass to comfort you. My knowledge of S-Logic is pretty basic but, from my understanding, the groves and cuts in the driver spread out and channel the sound. I imagine that statement doesn't give it justice, but that's the gist of what I get. As opposed to all these sound coming from one place, they are separated by the driver itself and channeled a certain direction. If your ears are in that direction, you are given an amazing sensation of sound. All the frequency ranges seem to compliment one another. I never hear fighting between them and I can always distinguish the sound they are playing. Ultrasone has a wonderful thing going here that, I think, deserves a lot more credit. S-Logic is that final element that allows all the precision boasted on the frequencies to work together in ferocious harmony. It's simply wonderful.
 
Vexare – Clockmaker
The piano in this song is very soft. It is used as a subtle background melody as the detail of the mids really is noticeable. The vibes that make up the drop are always pulling themselves around and dragging out as long notes and sound ever so powerful. They vibes pan left and right a lot and this doesn't take away from anything else. The rest of the sounds are solid in place and what needs to be panned gets panned. The glitchy high notes accent these strong vibes with so much precision and distinction. The crashes are smooth and clear. The mid bass hits and go away with the vibes for superb emphasis. The sub bass fluctuates with the mid range vibes and pushes deep when the size of the vibes really matter. Nothing overpowers anything else and it all sounds so amazing building up together.
 
Hulk – To The Stars remix
The guitar and percussion in the intro is all very quick and lifelike. The singing has the perfect amount of air to it and is very clean but forward. The kicks in this song play a big role and, like before, do a solid job of laying the “foundation” for the sounds they emphasize. The highs that glitch around do so excitedly but be sure to stay above all the other notes to just be for contrast. The drop has some of the most complex wobbles I've heard. They are very grimy, but smooth, but powerful. The Pro900s highlight these wobbles so, so well. They move around flawlessly and make themselves sound important. The bass is always changing to fit the vibe and goes deep when those wobbles really just need to hit you. The singing on top of the drop stays completely clear and doesn't get distorted or overpowered by the bass and all the other noises going. The drops is, all around, very complex and the Pro900s fit all the different sounds together just as they are supposed to.
 
Biometrix – Running
There's a lot going on in that Upper Mid Range here. The singing in this song isn't as natural as To The Stars. It has a bit of computer-ness to it as made by Biometrix. The background bass that comes with a lot of the non drop elements is subtle and stays back. The synth notes are clear and quick. The build up is full of high range frequency changes and isn't ever harsh and sounds far away instead of in front of everything. The drop itself has all the ranges in it. The mid range wobbles are just as smooth as the previous songs and the distinction between them and the big upper mid synths is superb. They don't sound like they affect one another. There's not as much bass in this song as the others. The bass here is used to add depth to those wobbles because those wobbles are supposed to sound intimidating and unavoidable. And that's exactly what happens.
 
Mitis – Don't Know
Mitis' songs are always super duper detailed. And are prone to sibilance. His songs are the only ones I have ever heard high frequency distortion on before. This song was particularly bad on the Pro900s before the burn in and Kees' mod. Now, 60 hours in, I don't have any distortion or sibilance at all. The sounds that were causing them are soft, clear, and detailed. They caused issues because of where they were actually playing. Slight high range glitches on the peaks of bass waves are, I imagine, tricky. But, as I said, the burn in and the mod completely got rid of the issue. Now, the rest of the song is just full of huge sounds. Mitis likes to use House'ish build ups in his dubstep and the Pro900s handle it easily. The constant punchy bass constantly stays punchy and the constantly busy mid range is constantly busy. There's no interruption for a confusion amongst anything and it flows very well detailed. The drop has one of the most powerful sounds in it I've heard. The scream of the 1khz vibe is huge and just encompasses you and makes you think of bad things. Then, it drops away and the upper mid range wobbles come in a just screw up your world with the bass kicking and roaring as the master of it all. It's all so perfect and I don't really have any other way of describing how well the Pro 900s handle such a powerful drop.
 
Mitis – Elevation
Similar to “Don't Know” in it has a progressive house intro and build up. There are a lot of sounds in here and, I'm probably starting to get redundant but, the Pro 900 keeps the sounds detailed and separate and the bass solid. The drop is full of frequency goodness too. It goes from lower mids to upper mids and back down and around and all over with different wobbles and vibes. The bass is introduced with a downward swipe of a vibe between the wobbles and rolls off of it with force and precision. Then it changes its attitude quickly when the wobbles come back and let them do their thing while acting as support. The kick adds that element of management to everything and stays in control without being in your face or too kicky and uncomfortable.
 
Mitis – Identity
110bpm is where's its at. I'm getting into my own production soon and this is where I plan on focusing. It was actually this song that made me realize this is where I most “feel” this kind of music. Mitis is a genius. A professional pianist turned EDM producer. And this song is proof of his genius. I'm going to go into too much specifics of how the Pro900 handles everything. It just does it perfectly as expected, remember that much. The mid range whine takes charge and reaches out for you but doesn't quite get there. The piano plays behind everything while atmospheric elements coat everything. The bass doesn't want to be too pushy as its there for purely for that extra sense of touch and interpretation as the mid range creates the mood. Wrapping this up, the drop boasts quick synths that pop up in front of the rest of the song. They synths are clear and, the whole song is created to perfection by the Pro900s.
 
Regarding the E17, Kees's mod, and the burn in.
I had the E10 before the E17 and, when I got the E17, the different was instantly noticeable. The bass boost on the E10 just didn't sound good. The E17's is much clearer and useful. The E17 seems to be a warmer style amp and it fits perfectly with the Pro900s. The bass and mids are brought to their full potential and the whole frequency range seemed more “at east” than with the E10s. The felt pads on the back smoothed out the effects of the bass, it seems, with the added mass. The felt pads on the driver cover smoothed off the highs and made them appear more natural and relaxed. But, with these 3^rd party tweaks, the most important is the burn in. From everything I've read, I'm not even half way through the full burn in and cycle and yet I can tell you, these thing change A LOT. Due to the technicality and precision of it all, it really has to work itself in. At first, the high were really harsh, the bass was muffled, and the mids were too laid back. Just messing around, I set up an EQ to try and see what could be done. I had the bass ranges at like +2db, the mids at +1.5db and from 1khz-10khz I had brought down 1-3dbs depending on where the harshness was. As hours were put on them, these adjustments were brought together into a flat line as they kept becoming more and more balanced.
 

 
Conclusion.
This has been a bit long winded, but I really wanted to be thorough in why and how the Pro900s suit EDM. So, to wrap it up quickly, let me just say that these are perfect for dubstep. You can try and take my explanations and see if that's what you're looking for in similar genres, but I really don't see how the Pro900s would be as beneficial to other genres as they are to electronica. The bass is deep, precise, and magnificent. The mid range stands out on its amount of detail and moves around flawlessly with quick pitch and frequency changes. The high range bright enough to not get left behind by the other ranges and just bright enough to play the “outside role” of accenting the lower frequencies.
 
Audio quality – 5/5
Comfort – 4/5
Design – 5/5
Value ($335) – 5/5
Overall – 4.8/5
 
Post introduction.
I hope you guys enjoyed reading this. If you have any questions, comments, or concerns, I'm more than happy to talk and open to criticism. So, feel free. I hope to be spending a lot more time with you guys as I continue my interest with audio and start getting into production myself.
 
Links and references.
My imgur gallery of the phones: http://imgur.com/a/eUfTC#0
Mitis' Soundcloud: http://soundcloud.com/mitis
Hulk's Soundcloud: http://soundcloud.com/hulk/
Biometrix's Soundcloud: http://soundcloud.com/biometrix/
Vexare's Soundcloud:http://soundcloud.com/vexare/
 
Take it easy, guys.
-Rath