First, some background on why I purchased this product: I recently got a new gaming laptop (an HP Omen 15-dc1062nr), and while I love it a lot, I discovered to my great dismay that the onboard audio from the headphone-jack has a very large, noticeable amount of background hiss/crackling/static when using my Fiio FH1 IEM's, which becomes even louder whenever I do anything at all that uses the processor (typing, web-browser activity, even just moving the mouse). I tried using my Hiby R3 as a USB DAC to fix the issue, but unfortunately, it seems to have intermittent issues with very large amounts of latency/lag, where sometimes I hear sounds up to a full half-a-second scream:) after the action in a game or video which caused them. Since my laptop is for watching stuff and gaming, not for music (I use my R3 for that), such an issue obviously makes the R3 useless for me as a USB DAC. I did some online research which indicated that such latency a very common issue when using the Hiby R3 as a USB DAC for computers, and is in no way an issue with my laptop itself.

So, I got the iEMatch as a way to attenuate the background-hiss! It arrived today, and here's what I can say about it:

This product is PERFECT! It does exactly what it is supposed to. On both the High and Ultra sensitivity settings, it completely eliminates any and all background-noise from my laptop's audio-output to my IEM's.

I now want to say something very, VERY important: Reviewers who say that this product "alters" the sound-signature are people with a poor understanding of audio science. I mean no offense towards them, but before making such a complaint, they should learn the truth about output-impedance and how it relates to impedance-graphs for headphones and IEM's. On the "high" setting (less than 2.5ohm output impedance), the iEMatch might indeed slightly "alter" the sound-signature if your IEM's are very low-impedance, in that it may add a tiny bit of bass-bloat, slightly narrow the soundstage, and possibly attenuate the treble a little bit. However, this is in no way a flaw with the iEMatch itself; it is simply the natural consequence of an output-impedance above 2ohms! A device which "alters" sound-signature would be something like an equalizer. The iEMatch does no such thing, it simply has certain impedance-levels which are clearly stated by iFi in its specifications. While my IEM's have a supposed/stated impedance of 26ohms, they are hybrid dual-driver IEM's and as a result likely have some large dips in their impedance graph, possibly to as low as 10ohms, in the frequency-range for the driver-crossover. As a result, any source with output impedance above 2ohms or so may slightly bloat the bass and attenuate the treble when compared to my Hiby R3 which has an output impedance of less than 1ohm.

On the "Ultra" sensitivity setting on the iEMatch from my laptop, the sound-signature is IDENTICAL to what I get on these IEM's from the Hiby R3 (I did a proper comparison-test with volume-matching and log-perceptual and constant-volume frequency-sweep files, as well as some binaural tracks). The only difference is a slight narrowing of the soundstage and decrease in clarity, but that was already true of my laptop's onboard audio and is simply because the Hiby R3 is a superior audio-player, and again it is no fault whatsoever with the iEMatch itself.

Some people say the iEMatch alters the sound-signature from equipment which is already VERY low impedance (like 0.2ohms or below). But that makes sense, and no one should be surprised by it, as in that case the iEMatch would just be attenuating volume while raising impedance. The product is intended for use with sources that have higher impedance than the setting being used on the iEMatch.

Essentially, any "changes in sound-signature compared to the true/original signature of IEM's" caused by the iEMatch are due to either the High Sensitivity setting still having overly-high impedance for some IEM's, or cases in which the iEMatch is used with very-low-impedance sources for which it was never intended for use.

On the Ultra Sensitivity setting, the iEMatch does indeed decrease/attenuate volume a very large amount (24db), so I need to turn my laptop's volume up to 90 or 100% for a lot of the stuff I watch or play, or sometimes even play things in VLC-player with a volume-boost or use an add-on to add gain when streaming in my web-browser. But that is, again, a consequence of the iEMatch doing exactly as it is supposed to, and is actually my laptop's fault for having too little output-power from the headphone-jack. It says right on the box that it attenuates volume by 24db on that setting, so voicing that as a criticism of the product would be unfair to iFi.

The fact is that the iEMatch does exactly as it is supposed to, and it does it VERY well. The features of being able to switch from balanced to SE output, as well as switch between two different impedance/attenuation settings, are very nice and make it mostly worth the price, as in that regard it is greatly superior to most audio-attenuators which people could make at home using resistors and soldering.

All that being said, the reason I give 4.5 instead of 5 stars is because the build-quality seems intended for home use rather than portable use, and I have a feeling that the device might break if it was being used for a portable device (like a phone or DAP) while constantly walking around with it and unplugging and plugging the iEMatch back in extremely frequently. For my purposes, in which it will spend 99% of its time plugged in to my laptop (which I basically use as a desktop PC, I only got a laptop because I occasionally require portability), the build-quality seems perfectly fine! But that may be a different story for people who want to use it portably; for them, I would strongly advise that they be very careful in handling the device when plugging and unplugging it on a regular basis into a DAP or phone.

SUMMARY: People saying this ruins the sound-signature need to research how impedance works in audio setups. This is an excellent product which does a very good job at exactly what it is intended for, and I would recommend it to ANYONE having issues with background-hiss/crackle from their audio setup on sensitive IEM's or headphones, as long as their source has enough output-power that they can still get enough volume with the attenuation from the iEMatch.

Since October, I have had the good fortune of having access to a pair of Alpha Dogs on-loan to me from a buddy of mine in these forums.  He and I had talked a lot about the kind of sound we each enjoy in headphones, and he told me that he was almost positive I would love the sound of the Alpha Dogs, and so he asked if I wanted to borrow them.  How could I decline?  As it turns out (and as will become clear in the following review) he was completely correct about how well the sound of the Alpha Dogs fits my preferences, and I almost certainly plan to purchase a pair of them (or the Primes) for myself once I can in the future.  So, on to the review, in which I will begin by covering every aspect of these headphones other than the sound, and then devote the rest purely to sound.  Please keep in mind that this review will not have a "comparisons" portion, because I have too little experience with Planar Magnetic headphones, nor with headphones in this price-range, to feel qualified to compare the Alpha Dogs to similar headphones.
 
Comfort
 
These headphones are SUBLIMELY comfortable.  The earpads are absolutely HUMONGOUS and so very soft and cushiony, and feel like plush pillows resting lightly around my ears.  The headband never seems to create that "pinching" feeling on the top of the head that some headphones get, and the clamping pressure is completely reasonable.  The one and only issue these can sometimes have with comfort is their weight:  Like most Planar Magnetic headphones, the Alpha Dogs have quite large and bulky earcups in order to accomodate the drivers, and I find that if I am very very physically exhausted it becomes a strain on my neck to wear them for a long time.  However, issues with comfort due to weight have only arisen once or twice during the four-and-a-half months I've had these, so I am taking off as little as I can from their comfort-rating in this review to account for that.  Do keep in mind, though, that very petite and/or very thin-built folks might have an issue with neck strain due to the bulk of these. . .for anyone for whom that is the case, that is a shame, because they are probably not going to have any luck when it comes to comfort from any planar-magnetic headphones besides perhaps the Oppo PM-3.

Keep in mind that it is because of the weight that I didn't give these a top rating for comfort, but that for me, the weight isn't an issue. . .I simply did that with the rating out of consideration of the fact that other folks might find the weight annoying.
 
Build
Immediately upon holding these in my hands, I knew they were incredibly sturdy.  Since they are not actually my own headphones, I have of course been extremely careful with them; however, I am absolutely positive that they could withstand all kinds of punishment (NOT THAT ANYONE SHOULD EVER TEST THAT! Seriously, don't, hahahahaha) and remain completely fine.  The steel frame for the headband is super-thick and sturdy, and the custom earcups made by Mr. Speakers seem very durable.  The stock cable is about as thick and durable as they come, and the engineers made a very, very good choice of cable-connectors on the earcups:  The way they screw and lock into place pretty much precludes any possibility of bending or breakage.

Basically, these seem like headphones that would last years even for a fairly irresponsible and clumsy individual.
 
Power Requirements
Don't believe what people say when they tell you that the Alpha Dogs need some kind of super-duper-powerful source in order to achieve close-to their full potential, although they can certainly benefit in some ways from a high-power amp.  They do just fine (with bass-impact at about 98% of what it is from a higher-power source, and everything else the same) driven straight from my Fiio X3 2nd Generation DAP, which has a power rating of a maximum of 200mW into 32ohms.  Even on normal/low gain, the X3ii is able to drive the Alpha Dogs loudly enough to become borderline-painful on most tracks with the volume at maximum, while with the gain on high, it drives them to truly-painful levels.  However, the X3ii does not give a lot of volume head-room for the Alpha Dogs. . .a decent amount, but not a whole lot, so if that's what you're looking for, something a bit more powerful is definitely recommended.  The guy who loaned me the Alpha Dogs is also loaning me a Schiit Asgard 2 headphone-amp, and I'm finding that the Asgard 2 pairs extremely well with the Alpha Dogs. . .not only is it able to drive them with a MUCH larger amount of volume-headroom than the X3ii (so if you're the kinda guy who likes listening VERY loudly, something like the Asgard 2 should go well with the Alpha Dogs) but unlike the X3ii the Asgard 2 has a 1/4" instead of a 3.5mm output, which in my opinion is preferable for a stay-at-home headphone like the Alpha Dogs--when I myself purchase the Alpha Dogs, I am going to be going with the option of the 1/4" cable rather than the 3.5mm, as it is much sturdier and more reliable in the long-run.
 
So in conclusion, a super-powerful amp is not necessary in order to drive the Alpha Dogs to truly loud levels; however, any source less powerful than say, a max-power of 150 or 100mW into 32 ohms will probably be too little for the Alpha Dogs, and will need to be paired with an amp, meaning that nobody is ever going to enjoy listening to these straight from a smartphone.  And if you want something which will give you lots of headroom for volume-control, the Alpha Dogs should be paired with an amp like the Asgard 2 which outputs over one whole watt (1000mW, for those who are not familiar with such unit prefixes) into a 32 ohm load.
 
Value
Honestly guys, I have too little experience with planar-magnetic headphones, as well as with headphones in the over-$400 price-range, to really judge how good a value these are myself.  However, people I know in these forums who ARE very knowledgable about such things all seem to be of the opinion (and have told me so) that all of Mr. Speakers' headphones, including the Alpha Dogs, are a very very good deal.  And in all seriousness, while they cost $500, they sound way more than even just twice as good as any of the $250 and $300 headphones I've ever listened to; so, I am going to give them a very high rating under the "value" category.
 
Looks
So here we get to the one and only truly "major problem" with these headphones, other than perhaps their weight for certain more petite and/or scrawny individuals.  Frankly guys, these headphones look dorky, bordering on downright stupid-looking.  My roommate and I think that I look like some kind of "mentally challenged spaceman" wearing them because of the huge awkward earcups and the guide-rails for the headband adjustment that stick up and out like antennae.  However, is any of this really an issue?  In my opinion no, considering that these are certainly not portable.  As long as I won't be wearing them out of the house, I don't care what they look like.  But I'm aware plenty of people might care, and so that's why I gave these a somewhat lower rating for "design" than in other categories.
 
Isolation
These isolate really well from outside sound, probably by virtue of the humongous cushiony earpads as well as whatever material the earcups are made from.  As soon as I put them on, all outside sound (especially in the midrange and above) is reduced drastically, and then as soon as music starts playing I basically cannot hear any outside audio-stimuli.  Very nice!  These are truly "closed back" headphones in a very, very real sense.
 
Sound
Okay guys, so here's the big part, the part everybody REALLY cares about!  As in previous reviews, I will first give a general overview of the sound, followed by a category-wise breakdown.

First of all, it is my opinion that for $500 these sound amazing.  I have listened to over-$1000 headphones at meets and stores taht at best sound subtly better than these, but not over twice as good.  Meanwhile, as I said before, these $500 headphones sound way more than just twice as good as headphones that are half the price, in my opinion.  I would classify their sound as slightly on the warm side of neutral, but still very close to neutral, with rolled-off upper treble characteristic of planar magnetic drivers, as can be seen here in the Alpha Dog (2014 model) measurements from Innerfidelity: http://www.innerfidelity.com/images/MrSpeakersAlphaDog2014.pdf  However, what I am hearing does differ in some ways from those measurements in the treble, as I will explain in more detail below.  Meanwhile, what really strikes me about the sound of these is that they manage to have quite good clarity, transparency, separation, and detail, all while managing to not sound overly-clinical, but rather to sound truly fun!  Finally, there's the soundstage and imaging, which are frankly MINDBLOWING (that one had to be in all caps, this is that darn serious) for a fully-closed-back headphone with isolation like this, and sounds very nearly like an open-backed headphone.
 
Bass
As is typical with Planar Magnetic driver technology, these produce very linear, clear, undistorted sounding bass.  While the frequency-response is somewhat on the warmer side, I would say that the bass still sounds quite close to truly "neutral" alongside the mids, to the point that if one were to (as I have) experiment by playing sweeping-test-tones ranging from 20Hz to 20Khz, it is incredibly difficult to even discern exactly where, if anywhere, the bass is "boosted."  Basically, the bass that comes from these, at least to me (YMMV) sounds exactly the way it is supposed to as any given track was mastered.  If the track has heavy, thumping bass, so do the Alpha Dogs, while if it has subdued, barely-audible bass, then that's what you will hear from the Dogs.  But when it needs impact, these have serious impact.  Frankly, the bass is wonderful.  I do SOMETIMES hear a very, very slight distortion/breakup down in the sub-bass when the volume is very very high, but I have to actually TRY to listen for it in order to detect it, unlike the very-audible subbass distortion which far too many headphones produce these days.  Meanwhile, at reasonable-to-loud volume levels, I never hear any distortion in the bass. . .it is pure, impactful, and clear, and I would give these a grade of, say, 93% (so an A but not an A+) for how they do bass both in-and-of-itself, as well as relative-to-the-mids.
 
I would also like to make a brief note about another big positive aspect of the bass from these:  IT IS TUNABLE, GUYS!  Yes, the Alpha Dogs come with a tuning-kit for tweaking the bass!  Personally, after trying it I adjusted the bass back to how it was when I first received them, as I liked it best that way---but that may simply be because my ears had already grown most accustomed to the signature at that point, as I did not try the bass-tuning at all until I'd already had them for a few weeks.  So, YMMV, and I'm sure plenty of you guys will find that even if the "default" bass does not quite fit your particular tastes, you will be able to tune it exactly to your liking   Heck, I mentioned the default signature is very slightly warm due to the bass, right?  I'm sure someone could tune these to have bass truly neutral relative to the mids, if they want, which should certainly be a huge, huge plus for a lot of audiophiles considering buying these headphones.
 
Mids
Just like the bass, and as is to be expected from Planar Magnetic drivers, the mids are nice and linear through their entire range (as well as relative to the bass), with the first hints of frequency-response roll-off not becoming at all audible until you get past the upper mids and into the treble at 2Khz or so.  The mids are clean, clear, and detailed, with a nice smooth sound.  Vocals, guitar chords, etc., they all sound awesome; as-in, the midrange sounds at least as good as it should for a pricetag of $500 on these headphones, and just like the bass is far better than one will get from the vast majority of traditional Dynamic-Driver headphones.  I would give the way these do the mids a solid 97% (A+) grade, as is to be expected from any planar-magnetic headphones.
 
Treble
Here's where we start to run into a little bit of an issue, as anyone who knows much about Planar Magnetic technology could have easily predicted.  The frequency-response, according to the measurements from Innerfidelity, starts to experience seemingly significant roll-off after about 2Khz.  However, I can barely, BARELY actually hear this roll-off at all, myself, until around the 7Khz mark or so, even when listening to equal-relative-loudness sweeping-tones.  In other words, the treble I am hearing sounds more like the uncompensated (grey colored) measurements from Innerfidelity rather than like the compensated ones.  So while there certainly is an issue with treble roll-off, it isn't "severe," in my opinion.  The treble starts to become at least somewhat-noticably rolled-off at 7Khz, but it is past about 9.5 or 10Khz that one finds truly serious roll-off in the treble.  So, what does this mean for the sound?  Basically, these headphones do bass and mids incredibly, the lower 50% to 60% (on a logarithmic scale) of the treble quite well, but have the upper-50% or so of the treble severely rolled-off, so that the overall sound is somewhat lacking in upper-end air and sparkle.  It only really becomes audible with things like cymbal hits.  Anyway, I would give the way these do the lower-50% (up to 8 or 9Khz) of the treble a grade of 85% (so a solid B) and the way they do the upper-treble a grade of 75% (a C).  Meh, what can ya do?  Treble-extension is the primary weakness of Planar Magnetic tech, and there's not much that can ever be done about it from an engineering standpoint.  I am 100% positive that the engineers at Mr. Speakers did the absolute very best they could to eke out the best treble they could from these drivers.
 
So what's this mean?  Basically it means that if you're a hardcore treble-head, these are not good headphones for you, and you should probably just stay away from Planar Magnetic headphones in general in that case.

One big plus to the treble from these, though?  It is very smooth and never ever fatiguing, without ever being strident.  I have also not once noticed any sibilance where it does not already exist in a recording.
 
Clarity and Detail
I don't understand how these manage to have such great clarity and so much detail while at the same time sounding fun and upbeat/energetic rather than clinical and analytic.  Sure, these headphones are not kings of detail and clarity, I mean they aren't STAX electrostats and they aren't Sennheiser HD800's, and they only cost $500.  But, wow, I can hear waaaaaaaaaaaaaaaay more detail in my music from these than I ever could before (with the exception of briefly demoing the HD800s, the Ether C's, and a few other summit-fi models), and the clarity is so very nice and sweet, as if I can really "hear into" the music.  Other stuff I've listened to has (to use a visual metaphor) been like looking at things without my glasses on, while listening to these headphones is like suddenly having my glasses on again to look at the world.  Meanwhile, headphones with summit-fi-level detail and clinical accuracy are like having my eyes replaced with those of an eagle, but I find that to be TOO much and downright overwhelming   Basically, these strike a fantastic balance between being fun and smoothed-out, and being clinical and super-detailed.  I don't know how else to describe it.  Of course, that detail and clarity unfortunately falls-off in the upper 50% of the treble, corresponding to the roll-off there in the Frequency Reponse; but what can ya do?
 
Dynamics and Speed
Wide and rapid swings in volume, super-fast sequences of wide-ranging (frequency-wise and volume-wise) successive notes, whatever, these can handle it all when it comes to dynamics and speed.  Everything sounds VERY energetic and fun on these headphones, and they ALWAYS make me want to start bobbing my head and tapping my foot
 
Soundstage and Imaging
It is in this category, more than any other, that the engineers at Mr. Speakers have impressed me to the point of absolutely blowing my mind.  I have seen several reviewers on here call the soundstage "congested" or simply "decent," but I honestly cannot see how they can think so when considering that these headphones are closed-backed.  These headphones have a soundstage ALMOST as wide as the soundstage of decent (but not great or high-end) open-backed headphones, and of course way wider than the soundstage of almost all closed-back headphone I have yet listened to.  And while the soundstage is lacking in depth compared to width, it is still quite deep for a closed-back, providing a good sense of separation between the instruments, at least to my ears.  And the imaging, it is INCREDIBLY realistic.  With songs that were very well-mastered in terms of the sense of space and position of the instruments, I often get that super-cool sense of almost (as opposed to a good open-backed headphone where it's no longer just "almost") being "in the room" with the instruments and being able to hear each of them from a slightly different direction than the others.  So, that is obviously a huge point in favor of these headphones, and of Mr. Speakers in-general. 

Let me tell you guys a somewhat-brief story (which you can feel free to skip, just skip this paragraph if you want) illustrating just what I mean about the soundstage of these headphones.  I have a friend, Alicia, who is not the least bit of an audiophile. . .for example, this girl totally thought, like most folks, that Beats were actually good headphones (because the Mass-Media says so, guys!!!!!) until I corrected her on that belief, haha.  And she is usually quite content to listen to, say, a pair of Apple Earpods (*barfs violently*).  So clearly, this girl knows nothing about hi-fi sound, right guys?  Anyway, so one day, she asked if she could listen to my headphones, since she sees how much they interest me.  First, she listened to the Sony MDR-1A, and then the Sony MDR-100AAP, both of which (especially the latter) are quite good closed-back portable mid-fi headphones.  The MDR-100AAP in-particular has a pretty good soundstage for a closed-back intended for portable use.  But, as soon as Alicia put on the Alpha Dogs, I could see on her face that her mind was blown.  After she was done I asked for her impressions, and this is what she said: "well, with those first two headphones it was like the sound was just coming from right here *gestures forming the shape of a very small box right in front of her face*, but with those big dorky looking headphones I tried last it was like the sound was coming from ALLLL AROUND ME *gestures in a big sweeping motion all around her body*."  Basically what I'm saying, guys, is that these have such a great soundstage for closed-back headphones that even a complete non-audiophile who knows nothing of sound-quality was immediately blown-away by it, and was even able to describe the actual concept/definition of "soundstage" as a result.  Pretty cool, right?
 
 
Conclusion/Summary
In conclusion, these are very, very nice headphones, in my opinion, for a stay-at-home user who wants a closed-back headphone for the purposes of isolation, while at the same time not wanting to sacrifice TOO much of the soundstage and imaging achieved by good open-backed headphones.  They have quite nice clarity, and great detail through the bass, mids, and low-treble.  The overall signature is very slightly warm, but can be tuned (YAY!) to be neutral through the bass and mids if desired, and has roll-off in the treble which starts to become quite audible around 8Khz due to the constraints of planar-magnetic driver technology.  And while not sacrificing the aforementioned detail and clarity, these are also very very FUN and dynamic sounding headphones, and invariably make me want to start tapping my foot to the beat of the music.  Finally, these are very very comfortable as long as they are not too heavy for a person.
 
So, the biggest points against these headphones would be: the aforementioned treble roll-off (although keep in mind that below 8Khz the treble is very good, and it is always smooth and non-fatiguing. . .personally, I prefer a rolled-off non-fatiguing treble rather than treble which is strident and piercing in an attempt to sound more detailed), the weight (for some folks, but not for me), and the looks which are simply dorky-as-heck
 
So, do I think these headphones are worth spending $500 on?  Definitely.  Will I be buying a pair of either these or the Alpha Primes for myself someday, after experiencing them as a loaner?  Oh yes, yes I will, definitely.  I've pretty much reached the conclusion that these are what I have always been looking for in stay-at-home headphones, and they or the Alpha Primes will almost surely be all I'll ever need (at least for a long long time) in that regard, once I can afford a pair myself.  My search for stay-at-home cans is over, and now I only need to find the "perfect portables" and my "ideal IEM's" to one day complete my collection.

Major Edit:  The cable on one side partially shorted-out.  Details below.
 
So first of all guys, I managed to get these for an incredible deal of only $50 at this site: http://www.shopdivvy.com/products/puro-sound-labs-iem500-studio-grade-in-ear-monitors-with-dual-dynamic-drivers  Pretty amazing, considering they go for over $120 on Amazon!  Anyway, moving on to the actual review:

These are great!  They have both pros and cons compared to my other IEM's, the Trinity Delta and the Shure SE215, which I will go into in the comparison section below.  So, to get started, let me go through category-by-category:
 
Value
For the price of only 50 dollars that I paid for these, they are insanely good.  That's all I can really say in this regard.  I honestly feel that even for the price of $120 on Amazon, though, they are still quite a good value
 
Sound
Overall Impressions:  These have excellent clarity and detail, a very neutral signature (which can be just a tad bright at times, however) but with powerful and well-extended bass when called-for, crystal clear sparkling highs with excellent extension, and a nice soundstage with fantastically realistic imaging.  They also have great speed, it would seem.  My one complaint would be that while these have fantastic detail and clarity, those aspects of the sound seem to come at the price of "smoothness," so that the sound can sometimes be a bit rough and unforgiving, at times even fatiguing (although not to a degree that detracts from my enjoyment).  Now, in order by category, in more detail:
 
Bass
Well-extended and very tight, without a hint of bloat, it is subtle but always audible on tracks without heavy bass, but able to become punchy and powerful on tracks where the bass is prominent, very much in keeping with the overall neutrality of these IEM's.  It doesn't really "stand out" like the bass of other IEM's I have heard, but is there when needed, and I enjoy it.
 
Mids
The mids are wonderfully forward, giving vocals and the majority of instrumentals a very pleasing and musical "in your face" kind of quality which usually sounds quite natural.  Not much more can really be said about the mids except that the upper mids (bordering on the lower treble) can, at times, become a bit strident and ever-so-slightly fatiguing. . .this may just be due to me having very high-sensitive ears, however, as I do recognize that overall, these are quite neutral.
 
Treble
These really stand out in the treble.  Wow, it's so crystal-clear and sparkly, guys!  The extension into the upper-octave is quite excellent and gives a fantastic "shimmer" to things like cymbals and high-pitched harmonics.  However, just like the upper-mids, the lower-treble can, at times, become just a little bit strident and fatiguing to my ears. . .meh.  Nothing to worry about though, especially once my brain gets used to it   The treble seems to be at about the same volume-level as the bass and mids, again in-keeping with the overall neutral tone of these.
 
Clarity and Detail
Holy moly!!!!  These things sound like pure crystal.  It is fantastic for well-mastered tracks. On the other hand, it is a bit unforgiving of more average-quality source material such as a lot of rap and hip-hop, but even then still sounds great to my ears   The clarity is to such an extent that it can sound almost "rough" at times, in keeping with the quality of recordings and how they are mastered.  Also, it seems to achieve such clarity at the cost of some of the smoothed-out "musicality" that I enjoy so much in other IEM's, as elaborated upon in my comparisons below.  I'd say that this is both a pro AND a con of the sound of these IEM's.  It is fantastic with very, very well-mastered music, and absolutely superb with classical/symphonic/orchestral pieces. . .now that I have these, I will not use anything else that I own for listening to Bach or Beethoven, for example
 
Soundstage and Imaging
The soundstage has decent width but is overall intimate, but pretty darn impressive depth that gives a good feeling of separation between instruments.  Color me impressed, as far as dual-driver IEM's go!  Meanwhile, the directional imaging is incredibly precise and realistic, and a real strength of these that is another reason I absolutely love using these for Classical music.
 
Speed
Truly excellent for dynamic drivers.  Nothing ever seems to "blend together" very much, not even in the fastest of heavy death-metal and thrash and such.
 
Design, Build, and Comfort/Fit and Seal
Well, these are pretty cool-looking, I must say, although they do tend to "stick out" a bit from the ears more than some other IEM's.  But the knurled aluminum housings are pretty darn cool looking, so I don't mind   Meanwhile, the actual build of the housings feels very, very sturdy.  HOWEVER, my one gripe with the build would have to be the cable.  It seems very thin, and is not confidence-inspiring in the least.  With a cable this thin, I wish they had made it detachable.  That being said, once shouldn't just a book by its cover. . .for all I know, the wiring on the interior of the cable may be of the highest quality!  I suppose that only time will tell, really.  Also, the cables get darn bad microphonics when worn cable-down, however it is very easy to wear these in an over-ear style and that solves the problem almost completely.

These are very comfortable!  Nothing more really needs to be said in that regard.  After a while wearing them, they really seem to "disappear,' so to speak. However, I had a hard time getting a truly proper seal with any of the tips that came with the IEM's, despite them coming with five different sizes of tips!  I don't know if this is due to the quality of the tips, the size of my own ear-canals, or what.  But, I was able to fit these easily with the medium-sized silicone-rubber tips from my Trinity Deltas (I use the double-flange tips with the Deltas, so I could spare the normal silicone ones), and with those I manage to achieve IDEAL seal and comfort from the IEM500's.  I would certainly recommend investing in some good aftermarket tips for these for many folks.
 
Major Update/Edit:  Just as I had feared, the flimsy cables were an issue.  The cable on one side shorted out (causing the music to play about 12db quieter on that side) after about four months of fairly steady use.  Not good build quality for the non-detachable cables.  For this reason I had to bump it down to four stars.  I only bumped it by half a star because I did get them for only $50.  But still, it seems silly of them to put a sophisticated dual-driver sound like this in a really nice housing, but with poor quality non-detachable cables.
 
Isolation
Again, HOLY MOLY!  I don't know how they made IEM's with vented dynamic drivers that have isolation this good!  It's really quite remarkable.  Once I get the music going with these, I can hardly hear ANYTHING in my surroundings, they isolate almost as well as the Shure SE215!
 
Microphone Quality
To be honest? No idea, and don't care.  Sorry guys
 
Comparisons
I have experience with two other better-than-average quality in-ears that I can compare these two:  The Shure SE215 and the Trinity Delta.  So, here goes:
 
Trinity Delta
I'd have to say these have both advantages and disadvantages compared to the Deltas.  They don't seem quite as well-built overall, especially the cables.  They do not have adjustable filters to change the sound-signature like the Delta.  The Delta, with stock or silver filters, have an overall warm (in the gunmetal case, TILTED towards almost neutral) signature, while with the purple filter are bright.  I'd say that the signature of the Puros lies somewhere between that of the Deltas with the gunmetal and the purple filters, right in the midst of "neutral-land."  The bass doesn't have the actual quantity it does from the Deltas with the gunmetal or silver filters, so they aren't as good for music like rap, hip-hop, and funk, but on the other hand I feel they do a good bit better with purely acoustic stuff and symphonic music, as well as many genres of rock and blues.  And it's not like the bass doesn't have impact, they just aren't warm/bass-boosted. . .but the bass is able to have powerful punch when called for.  They have more clarity and transparency then the Deltas with any of their filters (very noticeably more clarity than the Gunmetal filter Delta, and a subtle but still quite noticeable increase in clarity and detail over the silver-filter Deltas), but at the cost of that wonderful "smooth" timbre possessed by the Deltas, so it's a trade-off in that regard.  The soundstage seems about the same, while I'd say the directional imaging of the Puros is actually ever-so-slightly better than that of the Deltas and is a real strength of theirs.  Comfort is about the same, although it was easier to achieve a proper seal with the tips that came with the Deltas.  The Puros get worse cable-microphonics than the Deltas when worn cable-down.  The Puros do manage to isolate noticeably better than the Deltas, and I certainly prefer them in noisy environments.  Finally, the Puros are faster, and cause less "blending" of details in very very fast, busy tracks.

Overall, I'd say I don't prefer one of the two over the other, but rather prefer the Puros for the most well-mastered music which also benefits best from true neutrality, while I prefer the Deltas with any music that can benefit from a bit of "smoothing," as well as any music that sounds best when given a bit of a warmer coloration.
 
Shure SE215
Just like the Deltas, I'd say these kick the crap out of the SE215 in every single way while being in the same general price-range.  The only way they fall behind the SE215 is in terms of their isolation, and in terms of the impact/quantity of bass.  The SE215 are quite warm and a good bit bass-boosted, while these are neutral.  The SE215 do isolate even better than the Puros, and are better in the noisiest of external environments.  In terms of isolation, I'd rank the three: Shure SE215>Puro IEM500>Trinity Delta.  Like the Deltas, the SE215 are "smoother" and not as rough sounding as the Puros, but unlike the Deltas they are SO MUCH LESS clear and detailed that I much prefer the Puros over them for just about any genre.  The Puros have a better soundstage than the SE215, and somewhat better imaging.

Don't get me wrong, the SE215 are definitely some good IEM's!  It's just that the Puros and the Deltas are so much BETTER
 
 
 
Overall
These are really great, guys!  There's nothing more I can say here that I haven't already said.  Great clarity and detail, very neutral but perhaps a tiny bit strident at time, they have powerful bass when called-for and subtle bass otherwise, nice natural sounding mids.  They are fantastic for Classical orchestral music as well as acoustic, and for rock, blues, and jazz that sound best on neutral equipment.
 
Major Edit for those who missed it earlier:  The cable on one side shorted out (causing the music to play about 12db quieter on that side) after about four months of fairly steady use.  Not good build quality for the non-detachable cables.  For this reason I had to bump it down to four stars.  I only bumped it by half a star because I did get them for only $50.  But still, it seems silly of them to put a sophisticated dual-driver sound like this in a really nice housing, but with poor quality non-detachable cables.
 

I bought these on Brooko's recommendation, and they arrived earlier today.  I've gotten about six hours of listening with them, and oh boy, I am in love!  Normally I would not be posting this review so soon after getting the earphones, but here's the thing:  There's just about nothing I can say about these which would not already be 100% in agreement with the points in Brooko's excellent review of them, to which I would urge you all to refer!  There are just a few things I feel I can add beyond what Brooko said, mostly based on my own experiences with aspects of these earphones that may differ for others:
 
--I find that the two options for memory-foam tips included with these earphones are not as good as they could be.  They certainly aren't as good as the Olive Tips which came with my earlier purchased Shure SE215.  I wasn't able to achieve an especially good or comfortable seal using either of the two sizes of memory-foam tips that came with the Deltas.  That being said, I'm okay with that, because they come with three different sizes of silicone tips (which, granted, don't provide as good isolation as foam tips), and, most importantly for me, one pair of double-flange silicone tips which I find are quite comfortable and provide the best possible isolation.  I very much like the double-flange tips.  Moreover, using different tips, as long as the seal is good, does not seem to have any noticable effect on the sound from these.  I have, however, ordered a pair of Sony Isolation Tips (again on Brooko's recommendation) that I am going to use with these once they get here, for maximum comfort and the isolation that comes from a hybrid of foam and a silicone rubber sleeve.
 
--The filter options are a very nice feature.  I like the stock gunmetal filters best, but the silver filters are also very enjoyable.  Strangely, even though the silver filters are supposed to be the "fun" ones while the gunmetal are "reference," according to Trinity, I actually hear a bit more clarity and detail with the silver filters than with the gunmetal.  This seems to come at the cost, however, of some smoothness. . .the sound from the silver filters tends to be a tad bit harsher and grainier, a bit more prone to stridence, and a tiny bit more prone to sibilance.  Still very nice, though, and for those who want absolute maximum detail resolution without any concern for things like stridence, the silver filters should be awesome.  I cannot stand the champagne filters however.  This has nothing to do with the filters being "bad" or anything.  It's just that they are the bright/treble-leaning filters, and I've never really been able to stand bright sound signatures, as my ears are very sensitive to highs and fatigue quickly from bright sound.  What I can hear from the champagne filters, however, indicates to me that for true treble-heads and those who love a bright sound, they should be a truly excellent choice, as the clarity of the highs with them is top-notch.
 
--Cable microphonics are actually pretty darn significant with these.  However, I do not count this as a point against the Deltas, as this problem of microphonics is almost completely fixed by wearing them in an over-ear style, which is very easy to do and quite comfortable.
 
--The clarity is actually a TAD bit less than I would like.  These have less clarity, for example, than my Puro Sound Labs IEM500's.  YMMV, but I feel that while these have a very very nice "smooth" musical timbre, that smoothness does come at the cost of just a bit of clarity.  Not really a major problem, but for those who want MAXIMUM transparency these may not be the budget IEM's for you.
 
--The speed, mostly in the low-mids and the bass, is also a little bit less than I'd like, and on really really fast material like a lot of Death Metal, the bass notes tend to "blend together" so to speak.
 
Now, for any further detail on the sound, comfort, build, etc. of these, as I said just refer to Brooko's review.  On the other hand, though, there's one further thing I can offer you guys in my review, which is:
 
A Comparison with Shure SE215:
Well, what can I say?  In almost every aspect except isolation, these are a very significant step-up from the SE215.  Which is amazing considering the fact that the SE215 are indeed a very good deal at the $99.99 asking-price they can be found for on places like Amazon, while the Deltas are only 20 or 30 dollars more!  The Deltas have better clarity and separation, vastly better soundstage and imaging, tighter bass and sparklier treble, better (more forward, but not too forward) mids, and slightly better dynamics and attack than the Shure SE215.  They're about the same in-terms of comfort, although a bit more manageable in terms of ease of wearing them.  The included foam tips aren't as nice as the Shure Olive Tips as I mentioned above, but these come with a double-flange tip which is not included with the SE215.  They have customizable sound via the filters, which is not available with the SE215.  With the exception of not having detachable cables like the SE215, their build-quality seems better in every aspect.  The included carrying-case is hard-bodied, rather than soft like the one with the SE215.  Overall, these kick the Shure SE215 IEM's thoroughly in the rear-end (except, again, for having inferior isolation), despite costing only a little bit more.  As a result, I would consider them a SUPERB value!

Edit/Update:  This entire review has been completely overhauled now, as it was one of my true "noob reviews" from back when I knew pretty much nothing of real substance about good audio.  Silly me.
 
Comfort:
These things feel luxurious.  Perfect clamping-force. . .it is low, but high enough that they stay firmly on my head, even when I start bobbing my head or am walking around.  This is notable as I have a fairly narrow head.  It's very easy to form a good seal with these over the ears, and the space inside the ear-pads should be sufficient for most folks unless they have ears that are seriously quite large.  I can wear these for two, three, four, five, however many hours without it ever causing me any discomfort due to pressure.  The ear-pads are super-soft, like feather pillows. 
 
My only (slight) issue with the comfort is that the pleather on the ear-pads is prone to making the ears get warm and sweaty.  This is a common issue with over-ear headphones with pleather (rather than velour or alcantara or the like) ear-pads, so it's something I really don't mind very much at all, and it's not to an excessive degree since the pads are still quite breathable.  You'll notice that I still gave these headphones maximum marks in the comfort category on the rating-scale here, so obviously the warmth/sweaty-ears issue is only a slight one, IMO. YMMV, however.
 
People with large ears or ears that really stick out may have some issue though, as the earcups are somewhat-small on the interior and somewhat shallow.
 
Overall, these are actually the most comfortable portable headphones I have worn.
 
Build and Design/Looks:
 
These things seem quite sturdy.  The housings may be mostly plastic, but you can feel the sturdyness of the metal frame underneath, and while light they do have good heft.  I wouldn't recommend tossing them around or anything, but they can take their fair share of abuse.
 
They look amazing!  These are some real stylish headphones right here, seriously.  Sony hit a homerun with comfort and style for these!
 
 
Accessories:
The cables that come with these are very nice, in fact some of the nicest detachable cables I've seen with just-about any headphone in this general price-class.  It comes with two of them, both with the same type of very good wiring (which I don't think makes a difference to the sound I can hear, but makes them much sturdier and less prone to shorting-out, which is what matters) and one of them with an inline mic.  The audio-only cable is a model that is sold separately by Sony for over $50!
 
The case it comes with is basically just a bag.  No hard case.  Not a fan of soft carry-cases since they don't actually protect headphones.
 
 
The Big Part:  Sound------
 
Bass:  Boosted, especially the mid-bass, as is typical with "consumer" headphones and the vast majority of Sony's newer headphones.  However, it's not boosted to anything like basshead-levels.  It doesn't sound significantly bloated on most tracks and has a decently (but not very) solid texture, but can certainly get somewhat boomy at times and become fluid-sounding on bass-heavy tracks--again, typical for more "consumer"-oriented headphones, but leagues better than most in that regard.  The bass does not really noticably distort unless cranked to high (for me, near-painful) volumes, however.  Also, unlike the MDR-1R which it replaces, these have good sub-bass extension!  Thumbs up for that change, Sony.
 
Mids:  Quite prominent sounding, despite the boosted bass, due to the slightly rolled-off lower and mid treble.  Very smooth and creamy sounding.  It makes for a very pleasant, fun, and easy longterm listening experience, but I myself prefer greater levels of detail in exchange for some of that smoothness, as long as a headphone still sounds engaging and fun.  Some detail is certainly sacrificed in achieving that smoothed-out sound, especially a good bit of micro-detail.  But, for those who want something with very sweat and creamy mids (and treble, see below) which will always be completely non-fatiguing and make for very easy listening, these headphones are great.
There is some bass-bleed into the lower mids, however, in songs with heavy bass.  That's definitely a flaw with the lower-mids on these.  However, it isn't a huge amount of bleed like is heard from the vast majority of overpriced mass-consumer-oriented headphones out today.
 
Treble:  Slightly rolled-off, but not nearly as rolled-off as with the MDR-1R.  Very smooth sounding but still with decent levels of detail, much like the mids.  In fact, simply refer to my description of the mids in that regard to understand how the treble sounds with regards to detail vs smoothness.  The highs do also have a surpringly good amount of upper-end sparkle, extended well into the lower parts of the top octave, too!  They're able to give a pretty nicely shimmery effect to things like cymbals.  The sparkle is a nice surprise along with the powerful bass, giving them a somewhat v-shaped signature from the mid-bass up to around 11k or 12k (at least).
 
Isolation
It's decent.  Much better than, say, the HiFiMan Edition S (which works as an over-ear for me) in "closed" mode, but still beaten-out by many other closed over-ear models such as:  AKG K553 (with proper fit), PSB M4U 1, most closed Sennheiser headphones, and more.  I find it's perfectly fine for things like riding the bus and walking around town, though!
 
Soundstage and Imaging:  About medium-width for a headphone in this price-class.  Something like the AKG K553 or the PSB M4U 1 has it beat in that regard.  Pretty good depth, enough to get a decent sense of layering and some spatial separation between many instruments and vocals.  But there are closed headphones in this price-range (even the $165 price range it goes for used) which do have it beat just in terms of soundstage and imaging.
 
 
 
Note that these are overall a notably huge improvement in nearly every way (less rolled-off treble, more solid bass-texture, less bleed from bass to mids, less distortion, more clarity, a bit mroe soundstage) over the MDR-1R which they replaced in Sony's product-line.
 
Value:
At this point in time, these are outclassed by other headphones in the $300 price-range.  In some cases far outclassed, in my opinion.  If they want to keep having a headphone model in this price-range, Sony needs to update this to another MDR-1-something model.  So if you plan on getting new headphones, and are in the United States (Sony does weird things with pricing around the world, and they're cheap some places) I would generally say to not buy the MDR-1A, which still go for $298 in the United States.  Come on Sony, get with the times.
 
However, they commonly go used (in good or very good condition) for under $170 or even $160.  For that price, they are good headphones, and recommended as something to check out for any bass lovers (but perhaps not true bassheads) who still want good mids and upper-end treble sparkle and don't mind a somewhat more smoothed-out sound making for easy portable listening.
 
These will not satisfy the hardcore detail and uber-clarity oriented audiophiles looking for something in this pricerange, as they sound made for fun on-the-go listening rather than for analytical focus. 

I bought these IEM's on sale for $84.99 when I saw them in a store, as I knew they normally go for 99.99.  I believe they are a reasonably good deal for this price, but have some issues.
 
Comfort/Fit:  It is somewhat difficult to find a nice placement of these  with the wire over the ears that will stay firmly in place.  However, it is certainly possible to do so, and from what I can tell it should be possible for the very vast majority of folks to achieve a proper fit and seal with these.  Once properly fitted and sealed, these are very comfortable IEM's. . .I can listen to them comfortably for hours.  And I have small ear-canals and ears.  They come with a good assortment of variable tips. . .three each of silicone and foam tips, each in small, medium, and large sizes, so like most such IEM's, there are plenty of options for folks with very different ears to achieve a proper fit and seal.  Personally, I am deciding to stick to the medium-sized foam tips that came on them at the start, after some experimentation, as those seem to give me the best seal and comfort.  I can also move pretty vigorously and they don't fall out or slip out of place.
 
Design and Build:  They're neat in the clear design I got them in, you can see the electronics and the drivers inside!  The build is very solid, with the possible exception in the long-run of the cable connectors, which are little mini-coax types--prone to breakage with rough use or in the longterm.
 
Value/Price:  Well, these were a pretty good value at the price I got them for.  I'm not sure I'd recommend buying them at the usual price of $99.00, though--one can do better sound-wise for that price, and if you shop around one can do equally well in terms of build for that price, as well.
 
 
The Sound:  This is pretty good.  Some aspects of it are very good.  Most of the bass and most of the mids are quite good on these!  Buttery and smooth, with reasonable (but not very high) levels of clarity and detail.  Some folks will love it, others will probably hate it.  There does seem to be some bleed at the bass-mids boundary, though, probably indicative of some levels of IMD (since these do measure as having extremely low THD+N, apparently).  Also, the bass is quite boosted compared to the mids.  But it is reasonably solid given how boosted it is.  These border on the territory of being basshead IEM's, at least in my opinion.

The treble is rolled-off, but with a typical peak in the general neighborhood of 10khz and a few smaller peaks and dips below and above that.  The extension into the upper octave compared to the rest of the treble is surprisingly good given the price-tag, but is nothing truly special.  Like the mids and bass, the treble is buttery-smooth and reasonably, but not especially, detailed and clear.
 
Overall, these sound very smoothed-out.  One cannot hear too "deeply" into the music, and it is not really analytical.  Some may really like that.  Personally, at this point, I prefer something that is still engaging and fun, but more on the analytical side.
 
The soundstage is surprisingly pretty good, but nothing special, except when you consider how isolating they are with proper fit--They easily get over 25 to 30dB or more broadband isolation, and have a single dynamic-driver design, but still do have a sensation of soundstage and a bit (but not much) of an out-of-head sound.  It's honestly quite hard to get well-built IEM's with good soundstage in this price-range (I did finally find the Trinity Delta for only $99, which has amazing soundstage for the price, though), so it's nice that this does have a perception of soundstage.  One can even hear decent layering and such.  But the soundstage itself is very narrow and has only moderate depth (to my ears).
 
 
In summary, I'd say these do a few things well; the build (for the price, a lot of truly-shabbily-built IEM's in this price-range), the isolation (awesome), the fact they've got some layering to the soundstage, the bass and mids (aside from their boundary with the bleed), and the overall smoothed-out quality which I myself do not like but some might

A friend of mine has these, he received them as a gift from someone who purchased them for 200 dollars without any proper research first, which was probably a big mistake on their part.  I've had quite extensive chances to listen to these and compare them to my V-Moda M-80s, and can honestly say that as far as closed-back on-ears for under 200 go, the sound on these doesn't come CLOSE to teh quality of the M-80s, and these cost 50 dollars more!  The only way these beat the M-80s is in terms of comfort. . .the one thing I can say with the utmost positivity about the P3's is that they are SUPREMELY comfortable for a pair of on-ear cans.  The fabric on the earpads is nice and soft and comfortable, and breathable to the extent that it doesn't make your ears hot and sweaty even outside in warm weather.  Despite that, they provide quite good isolation for a pair of on-ears!  Nice.

Now for the sort-of bad part, guys.  These cans were a big miss on Bowers and Wilkins' part, in my opinion.  There is a massive amount of bass-bloat. . .the bass, I will say, is almost completely lacking in distortion, unlike what you hear in most bass-bloated cans (eg. Beats or Skullcandy), but is simply overwhelming and drowns out the mids.  The mids and highs DO have decent detail, but this is mostly hidden by the bass.  Also, there is a strange somewhat "muffled" quality to the sound, which I suspect is due to the design/engineering of the earpads, perhaps the material used in them, combined with the overall bass-bloat.  These have quite good soundstage and imaging for a pair of closed-back on-ears, but this is basically ruined, at least for me, by the loss of detail resolution due to bass-bloat.  I would be happy to listen to these for Rap and Hip-Hop, but not for much else, really.
 
Finally, the build quality of these is seriously questionable.  These cans retail for 200 dollars, and yet have a non-detachable, thin and flimsy cable which splits-off and connects to both ears rather than just one side.  If a company is going to make a pair of headphones with a non-detachable cable (which is a pet peeve of mine, anyway) they should at least make the included cable nice and sturdy, but in this case, it seems only slightly better quality than what you get with someth8ing like stock Apple Earbuds that come with an iPod, which on a pair of 200 dollar cans is, in my opinion, unacceptable.  The build of the rest of the cans is quite nice. . .metal frame, teh fabric earpads, reliable folding hinges. . .but is ruined by the flimsy cable.  In fact, my friend, who certainly is not an audiophile and thus does not mind the bass-bloat on these at all, is wanting to get new cans now because the cable is shorting-out and has become temperamental, after only about eleven months of use!  I think that for 200 dollars, Bowers and Wilkins could have put a lot more effort into the quality-control for teh build of these things.
 
Overall, I'd say you can do much better than these for the price that they go for, or really, can do much better than them for a little over HALF their price.

I got a pair of these new on Amazon about a month and a half ago.  I thought they sounded great for a pair of closed on-ears, and were pretty decently comfortable to the point that listening to tehm for two hours straight, I had no real issues.  The isolation is also pretty good for closed on-ears, considering the lack of extreme clamping force (which is good for comfort, of course).  Good frequency-response and detail, and they have a nice soundstage for headphoens in their class.




Unfortunately, however, I think the manufacturing quality-control on these may not be up to Sennheiser's usual standards!  You see, after just two hours of normal use from the heaadphone jack on my laptop (was using WASAPI, of course) which certainly is not powerful enough to over-drive them, the right driver completely stopped working!  I suspect it was due to faulty wiring to the right side coming from the left-driver where the input jack is located.  Anyway, this obviously ruined teh headphones for me, and I returned them to Amazon for a refund.  Not wanting a repeat of the same experience, I bought a pair of V-Moda M-80s Crossfades insteaad, which I can honestly say are quite superior to the Momentum on-ears in almost every way except isolation. . .soundstage better, detail a tad better, about equally comfortable for me, better looking in my opinion, slightly nicer frequency-response (slightly flatter, but still nice punchy bass, although the treble on the M-80s might actually be a TAD bit inferior to the the Momentum on-ear), superior build-quality and, clearly better quality-conrol with the manufacturing.  I'm honestly GLAD that my Momentum on-ears turned out to have faulty wiring, because it's as a result of that, that I now have the M-80s instead.  However, the M-80s are, depending on the COLOR of the Momentums (strangely enough the price varies WIDELY between the different color options, weird) a tad bit more expensive, but I'd say totally worth it.  Did I mention the M-80s also come with much higher quality cables?  It's true that the Momentum on-ears come with one extra cable, but both cables seemed quite typically flimsy to me.


 


In conclusion, these are certainly good sounding and comfortable, and even reasonably well-isolating headphones, for their class and price-point, but there are others available in the same general price-range (such as the V-Moda M-80) which are better, and I'd be quite wary of the wiring quality in these based on the experience I had with the right driver failing.

So, first off, I must say that for 200 dollars (or 170, in my case, for a unit that was previously a store-display model), you CANNOT go wrong with this superb little DAP.  The soundstage and dynamics, detail separation, and overall frequency-response are FAR AND AWAY better than what you hear in something like an iPod, Zune, or Smartphone.  That being said, does it sound as good as a 1400 dollar hi-Res Walkman, or a 1000 dollar Astell and Kern or HiFiMan DAP?  No, of course it doesn't, but you're only paying 200 bucks for it so just sit back and enjoy it, guys   The bass is very accurate, in fact, the WHOLE frequency-range seems incredibly accurate on this through my V-Moda Crossfade M-80 headphones, but I will say thaty the treble seems just a LITTLE bit bright, to the point where when it's on a high enough volume that the mid-range doesn't QUITE hurt my ears yet, some of the higher treble-notes sound a bit painful.  But it's probably not good to listen to it that loudly for extended periods of time anyway, so it's not much of an issue.  The sound also is a TAD bit more analytical as opposed to warm or fun, but many people may like this. . .personally, I'd prefer a bit more warmth, but heck, this is still WAY more fun-sounding than my laptop's on-board sound, or the sound from my old iPod for that matter!  Then there's the fact that unlike the X1, you can use this as a USB DAC for your computer. . .and oh BOY does it improve vastly upon the onboard sound in my laptop!  As a result, you're basically paying for two devices in one, both a DAP AND a DAC, which only serves to make this an even BETTER value for your money.  It is also quite good at driving headphones at al different impedance levels, even without an amp, although I'd imagine that if you're using something with an impedance int he range of a few-hundred ohms, you probably want to pair this with an amp.  The UI is quite customizable, and it has a very nice built-in equalizer.  The build-quality is excellent, all solid-aluminum, and it comes with some nice accessories: a silicone carrying-case, and a line-out with gold-plated connectors.  Also some stickers that personally I think are kind of silly, haha.
 
All that being said, the X3 2nd Gen certainly has its issues, although nothing that I find to truly be a nuisance.  The UI seems to "glitch out" sometimes, and in very random ways that I can't even quite describe, leaving me no choice but to force a shutdown and restart the device.  I use this for at least six hours a day, and the glitches seem to occur maybe every third day or so. . .not too bad, really, it hardly bothers me at all.  Right now the device is only on v1.1 of its firmware. . .I'm sure that the glitches will be fixed in future updates from Fiio!   UPDATE (September 10, 2015): Sure enough, since installing the newest released stable firmware, v1.3, for the X3ii, I have not experienced a single glitch, either in DAP mode or USB DAC mode.  Also, it seems like things lag a little bit less when browsing through files and skipping songs.  This is still a very early version of the device's firmware, but already seems to have fixed the vast majority of stability issues.  Very nice job, Fiio programmers!
 
I would recommend this device for ANYONE looking to buy a good DAP for anywhere under 300 dollars to vastly improve upon the sound they get from their smartphone, laptop, or other such devices.

Note:  The entire original review has been mostly deleted and overhauled.  These were the first at-least-somewhat-good headphones I ever purchased, and I was way too hyped and knew way too little when I wrote this review.
 
I bought a pair of these used for $70 (months later, I sold them for my roommate for $50), and for that price and being on-ear they are good headphones.  Here's a breakdown of their different aspects:
 
Build:  These are ridiculously well-built.  Pretty much all metal construction, and tested under ridiculous conditions.  They can apparently even be stepped on, repeatedly, and often still be okay (not that I ever tried that).  Based on how sturdy they look and feel, that is seriously believabvle.  They are like some kind of armored-headphone.

Oh, and the cables are apparently tested for being able to work after a million bend-cycles.  I've been heavily using the second cable from the headphones as an input to my car stereo for over a year, and it still works well.
 
Design:  In my opinion, these things look really cool!  The all-metal construction and their shape is very "stylish utilitarian" looking, I would say.  Moreover, the covers on the enclosures can be customized with a number of V-Moda's own designs, as well as with any user-submitted design!  I never went as far as ordering the custom plates, but it's a very cool option.
 
Comfort:  For me there were some issues here.  On my head, they at first seemed to pinch a little bit at the top of my head.  However, the excellent build-quality makes it easy and safe to slightly bend the headband outward a few times before each time putting them on.  After a few days of use, they adjusted to my head and were comfortable.
 
Sound and Isolation:  These do not isolate very well, of course, being on-ears.  But they isolate well for what they are (although not as well as the most isolating on-ears).  With the music at a decent volume, most reasonable outside noise is not audible.  These will not isolate from somewhat-louder noises like a well-isolated closed over-ear will.
 
--Bass:  These have boosted bass.  For how my tastes developed over time, it eventually seemed a bit much.  I would almost consider V-Moda's headphones to be basshead headphones, to be honest; if you're a basshead looking for a cheap super-portable and sturdy on-ear, a pair of these bought used is great to consider.

The boost seems to be centered somewhere around 80 to 110 or 120 Hz, to my (not super-precise) ears. 
 
However, like with many on-ears, the bass does break-up (distort) to some audible extent at high volumes (for me, borderline-painful or downright painful).  Even at the loudest volumes I like to comfortably listen to (loud end of moderate volume), the sub-bass (on tracks with lots of sub-bass rumble, and with test tones) does sound a bit "muddy."
 
But overall, the bass does have an impact to it that can be very nice.  I imagine people who love bass will enjoy it a lot for this price.
 
--Mids:  Can't hear any distortion in the mids.  They sound pretty nice, but a bit congested.  Also, the mids don't seem flat, but rather seem to favor the low-mids, so that overall these headphones are definitely quite warm--another bonus point for these for all the bassheads out there!
 
--Treble:  Sounds about the same level as the upper mids, to me.  They have a peak at the 10 or 11khz band, which gives these good sparkle.
 
--Clarity and Detail:  Somewhat impeded by the congested sound of these.  This is very common for on-ears, especially in this price-range.  The detail is pretty good.  Micro-details are, as expected, smoothed-out though, sometimes inaudible.
 
--Dynamics:  These have quite good dynamic impact, actually.
 
--Soundstage and imaging:  The soundstage is pretty good actually in terms of width and depth!  But, the directional imaging for spatial-separation between elements is slightly "blurred," in correlation of course with the overall congestion of the sound.
 
 
Value:  Honestly I do not like the sound very much given the resources that V-Moda put into this headphone, as I know for a fact it is possible to get a clearer and less-congested sound in on-ears, especially for the original price of these (over $200, actually) when they first came out.  However, this is largely because I am a clarity-junkie.  For those who want plenty of bass-slam and warmth with flat mids and treble, with a bit of extra upper-end sparkle, and like good levels of detail but aren't after levels where they listen analytically/clinically, then these headphones are great.  Especially for the price they now go for used (in the $70 to $80 range)!  I highly anticipate that used M-80's which still work, will continue working fine for years (I bought mine used and it still works over a year later) in the majority of cases, due to the amazing build-quality.    For this reason, I give the M-80 a high rating for its value.
 

Overall:  I give these four stars.  I don't like the sound much myself, due to the bass becoming boomy and breaking-up in the sub-bass.  I also prefer more clarity and soundstage with less congestion, which is possible in on-ears at this price.  However, they have a very good value now used, and unbelievably good build.  Also, they look awesome!  So, four stars.  I would put the sound at 3.5 stars (to my ears and preferences) with the value at 4.5 stars, and the build and design at 5 stars.  To me the sound is the biggest part, and that's what brings these down to a four-star rating.