Introduction​

 
Finding a great isolating closed headphone has been my white whale for years. I’ve gone through the B&W P7, NAD Viso HP50, Denon D2000, Fostex TH-X00, a modded Fostex T20RP, modded XB950BT, and a Beyerdynamics T5p in my hunt. Every closed headphone I’ve tried had their own weaknesses and it became a game of trying to find out which tradeoffs I was willing to accept.
 
When I saw hype about the Cascadia Audio Talos, a new T50RP mod, I was intrigued. Most T50RP mods I’ve tried, like the Mr. Speakers line, disappointed me in the treble. The Talos was a v-shaped, fun T50RP tuning -- unique, and more affordable than most T50RP mods. This was the first bright T50RP mod I’ve seen, so I needed to see if they had nailed the treble properly.
 
I purchased the Talos a week ago and I’ve spent a lot of time with them now. I’ve been using them as my daily drivers at home and work.
 
Long story short, the Talos is a bargain at its current price of $250. It’s a delightful headphone that works great in the home or office. The bass slams hard, the treble shines through, and they have all of the markings of a great v-shaped headphone.
 

My Biases​

My daily driver for the past several years has been the HD800. I’ve used various mods on it, but I am currently using it with equalization to level out the treble peaks and boost the sub-bass. These are my reference most of the time.
 
I tend to enjoy deep, extended, and even emphasized sub-bass. I like treble both neutral and emphasized, but I am bothered if the treble is too recessed or recessed with peaks. The DT990 is too hot in the treble for me, but I enjoy almost everything from darkness of the Audeze LCD-2 pre-fazor to the bright HD800 stock.

Build Quality and Comfort​

Cascadia Audio replaced the stock pads on the T50RP with Brainwavz hybrid pads -- velour on the head, pleather on the side. These pads are very plush and big. Combined with the medium clamp of the T50RP headband, these are some of the most comfortable pads I’ve worn on a closed headphone.
 
 
 
 
There is a leather headband on the headphones under the stock headband. Thanks to the headband, the headphone distributes its weight more uniformly than a stock T50RP. The Talos has some heft to it, but the headband makes them very comfortable for a heavier headphone.
 
The headband adjustment is the normal T50RP sliders. It’s a simple and effective system. You push the headband up to the right height on both sides and that’s it.
 
Other than that, these feel like a standard T50RP. They’re built solidly and have a removable cable. They do use stickers for branding, but it’s a minor aesthetic detail. I personally use the V-Moda Audio Only Cable with them, but they come with an orange angled short cable and a black 1/4in longer cable.
 

Sound Impressions​

For a $250 closed-back headphone, the Talos sounds great. They’re very fun sounding, but maintain a tasteful v-shaped tuning. The DT990, for example, is a fun and v-shaped headphone but overdoes the treble. I had to mod my DT990s to be a bit more subdued to enjoy them, but the Talos are great without mods.
 
Most planar headphones have linear, extended bass, but the Talos opts for an emphasized punchy mid-bass. If you’re a basshead, you’ll love the Talos’ impact. The sub-bass is a few dB quieter than the mid-bass, but still rumbles strongly. The bass quality is solid, but not phenomenal. The bass is a bit looser and warmer than the bass on the NAD Viso HP50. The bass presentation is more musical than tight and detailed. That said, the bass quality is quite controlled, just not top of class.
 
The Talos presents more natural mids presentation than most T50RP mods I’ve heard. Due to the v-shaped tuning, the mids are a bit recessed, which can be noticeably heard when listening to a select few female vocalists. That said, the mids are clean and have a rich tonality to them. Overall, I find the mids to be competitive with other closed-back competitors in its price bracket.
 
The treble is unlike any other T50RP mod I’ve heard so far. It’s very bright and forward as part of the Talos’ fun sound signature. I normally find T50RP mods to be too dark, so it’s a welcome change. It’s bright, sparkly, but doesn’t run too hot and provides solid detail and air. I don’t find the Talos to be fatiguing despite the bright tuning.
 
The soundstage isn’t the widest I’ve heard from a closed back headphone, but it is above average. The Fostex TH-X00 and the Beyerdynamic T5p both cast a wider image, but the TH-X00 is more expensive and leaks much more sound and the T5p is a significantly more expensive headphone as the Beyerdynamic closed flagship.
 
The Talos sounded great out of every amplifier I’ve tried and don’t seem to be very source dependent. I have to crank my amplifier a bit to get these to a good volume. Although they can work out of a mobile device, I strongly suggest pairing them with an amp. I personally found even the Fiio E10k was sufficient.
 

Closed Back Comparisons​

Vs. TH-X00

The Fostex TH-X00 had more sub-bass slam and slightly cleaner bass than the Talos. The mids clarity was roughly the same, but I didn’t notice any dips in the mids. The upper midrange on the TH-X00 struck me as being a bit more emphasized and shouty, but the Talos was brighter in the treble. The TH-X00 had a wider soundstage, but it also leaked a lot more sound and isolated much worse. On a technical level, the TH-X00 trumped the Talos, but the Talos’ superior isolation is why I use it in the office.
 

Vs. NAD Viso HP50

Like the TH-X00, the HP50 trumped the Talos in terms of sub-bass extension and bass clarity. Noticeably, the Talos sounded more open and had a more air-y sound than the HP50. I preferred the treble presentation on the Talos, as parts of the treble sound recessed on the HP50.
 
Both headphones isolated very well, but the HP50 was much less comfortable. The HP50’s pads are thin and presses the headphones against my ears. The Talos’ pads were much more thick and soft and stopped the drivers from pressing against my ears. The HP50’s headband touches your head at a point, placing all of the headphone’s weight on the very top of your head. To contrast, the Talos suspended headband distributes the weight better across your head. Even though the HP50 was the lighter headphone, I found the Talos to be much more comfortable, both on the ear and on top of the head.
 

Vs. Beyerdynamic T5p

The T5p and the Talos are both very comfortable headphones. The T5p is much lighter than the Talos and has bigger pads, but the pads are less plush. Overall, they're both supremely comfortable over-ear headphones. My T5p has a more lean sound signature. Both the Talos and the T5p have resolving mids and treble, but the T5p definitely edges out the Talos in terms of bass quality. The bass is tighter and more defined, while the Talos is a bit looser. The soundstage on the T5p is wider is wider than the Talos, although that should be expected given the price difference ($1000 vs. $250).
 

Talos - Summary​

 
The Talos delivers a killer listening experience without being picky about source. It’s not quite a super resolving, detailed reference headphone . . . but it’s also $250 fun closed headphone, rather than a flagship reference. Sure, the bass could be tighter or the mids a bit more full, but . . . it’s a $250 fun closed headphone. For that price, these are wonderfully detailed and transparent. Honestly, you’d be hard pressed to find a better closed headphone for even $500. Personally, the Talos have dethroned the NAD Viso HP50 as my isolating closed back headphone of choice.
 
Cascadia Audio has done a great job with their first headphone and I look forward to seeing what headphones they bring in the future.

Introduction and Design
I picked up the Woodphones 10 months ago, so I've had quite a bit of experience with them in my collection. Despite me having sold off most of my closed headphone collection, the Woodphones will remain in my collection forever as a beautiful closed headphone with some solid positive sound qualities. 
 
What really drew me to these headphones was the design and the customization options. FreqWood (then Architectural Woodphones) tried very hard to really put the experience with these headphones amazing. They came with a little plaque with my name on it as well as my name being burned on the inside of the headphones.
 
The woodwork looks great, the colors work well, and the pieces all fit well together. The leather headband is designed after the auto-sizing headbands and fits my head nicely (despite me having a small head). The Beyerdynamic pads are soft and comfortable. 
 
It is worth noting that Blake has made improvements and is working on Fostex-based designs on his Woodphones now and that my review is on the older models.
 

[size=xx-small]This photo came off of the Facebook page for the Woodphones -- it was far nicer than any of the pictures I was able to take and illustrate the beauty of the headphones far better than my amateur images.[/size]
 
 
Comfort
 
I was pleasantly surprised by how comfortable these headphones were -- they are all-day headphones. They are the lightest headphones in my collection and use what appears to be Beyerdynamic velour pads. The pads are soft, the clamp is low, and they're light. The only issues I've noticed with regards to comfort are that my ears do warm up a bit quicker than expected in the velour pads and that occasionally my ears touch the inside wall of the headphones. Besides those minor issues, though, these are some of the most comfortable closed headphones I've used.
 
Sound Quality
Bass:
The bass is emphasized on these headphones, helping to create the v-tilted sound signature. Unfortunately, the bass is probably the weakest part of these headphones -- it is emphasized but the quality of the bass is rather low. It sounds very "one-note" and thumpy, relative to headphones with more articulate bass.
 
When I equalized the bass down a bit, it reduced how noticeable the thumpy effect was, but did not remove it completely.
 
Mids:
The sound signature underemphasizes the mids, giving way to the emphasized base and highly tuned treble. With regards to clarity, the mids do come out cleaner than most of the "budget-fi" headphones, but they don't quite reach the level of clarity seen in the higher end headphones.
 
Highs:
The highs are very emphasized on this headphone, particularly in the 6khz range. When listening to music, expect to hear the cymbals really shimmer out. It gives a bit of a faux-detail effect as seen with the KSC75, giving a sharp edge on most songs. In terms of treble-heavy headphones, the tuning was nicer to my ears because they avoided sibilance, despite the treble emphasis. I did not find the headphones particularly fatiguing, but I could definitely see treble-sensitive listeners having an issue with the sound signature. Overall, these are one of the brightest headphones in my collection.
 
Other Sound Thoughts:
 
I'm not sure if it is a result from the sound signature or the design that causes the sound stage to sound wide on the Woodphones, but they sound more akin to a semi-open headphone in terms of soundstage -- although the bass issues muddle the overall imaging of the headphones.
 
Closing Thoughts:
 
To be brutally honest, at their original $200 price point, the original Woodphones were overmatched in terms of the acoustics. That said, the experience of ordering them, getting everything customized with a customized design, and their light-weight comfort makes them overall a winner and a very unique headphone. Although I would advise against purchasing one as a primary high-end closed headphone, I would heavily suggest them to anyone looking for something different and comfortable. 

Introduction and Design
I got the Exodus because it was on sale for $49 like new, which is a phenomenal price, and I used them to replace my Brainwavz HM3 as my on-the-go portable. When I received it, the plastic wrappings on the headphone itself hadn't even been broken. I loved the overall look and feel of the headphones before I put them on my head. They felt pretty sturdy, but just from how they look, I wouldn't want to use them as a beater pair of headphones to toss in my bag of anything like that.
 
Comfort
 
When I put them on, I immediately noticed the clamping force. I have a pretty small head (the smallest size on most headphones almost fits me well) and I can only imagine how much worse the situation would be for someone with a large head. That said, I can shake my head around and run around and not feel like these guys are leaving my head -- a nice quality for a portable on-the-go pair of headphones. I haven't used them for an extended period of time to see how much they hurt my ears over the long run, but they've treated me nicely for the short durations I've used them. 
 
Sound Quality
Bass:
The bass response is pretty nice on these headphones. I don't typically buy portable headphones, but these extend deeper in the bass than any of my other headphones. My initial listening made me feel like they sounded pretty much linear into the lowest audible bass frequencies. For a portable pair of headphones, that type of deep linearity is pretty rare. I was pretty happy with the bass response, even if it was a tad more emphasized than I would have liked. I wouldn't classify the bass as tight or particularly boomy. There was a bit of a mid-bass hump that showed up a lot with bass drum kicks. The bass isn't particularly articulate as you get down to the lower frequencies.
 
Mids:
The mids were a pleasant surprise. I actually found them to be clearer than my Denon D2000s, actually. They were not quite as clear as my Fostex T20RP's mids, but I was pleasantly surprised. The clarity in the mids definitely blew out all of my cheaper headphones out of the water (keeping in mind that I bought these at $50). They were nice, lush mids that were part of the very full sound of the headphone.
 
Highs:
The highs are the main issue with the headphone. They sound like they lack the air that comes from good treble extension. I feel like someone took a chomp out of the upper frequencies and lost all of the sparkle in the highs. Cymbals and such just don't sound like they should, they lack the shimmer that you would hear even on a neutral headphone. Without the highs, the music is just a bit dull. I also noticed that when I equalized to the point where I felt the highs were at a nice point, the headphones became sibilant -- I think there is a little bit of ringing near the upper treble frequencies. 
 
Other Sound Thoughts:
Being a closed on-ear headphone, I expected a pretty mediocre soundstage. It's basically what I got. The soundstage is like an ATH-M50's soundstage -- very narrow. The instrument separation isn't all that great partially as a result of this and also as a result of the somewhat inarticulate bass and the rolled-off upper treble. The headphone by itself when you're just listening without analyzing much sounds quite nice -- the overall tonality of the headphone lends itself to long listening pretty nicely actually. I can't see someone becoming fatigued from the sound signature of these headphones.
 
Closing Thoughts
At $50, these represented the best value I could get in a portable pair of headphones. They were basically competing against headphones like the Koss DJ 100s in that price bracket, and they did a number on the DJ 100s, in all honesty. The bass response is nicer and they felt more detailed. The vocals are not quite as forward and shouty and feel overall just better put together compared to those Kosses.
That said, when you push them out of that price bracket into the $150 bracket, the sound just doesn't feel like one of those "THIS IS AN AMAZING DEAL" headphones. When I was originally writing this review, I was thinking that they were actually behind the curve for their price, but then I realized that, among the light-weight portable headphones, Among the light-weight headphones which I know of and that I would use on-the-go, they are actually quite nice. I'd easily pick these over a pair of Grados or an AKG K81DJ or a Fischer Audio FA-004. I have not heard the Audio-Technica portables. With that realization, I bump these up to a 4 stars out of 5 for being a nice pick if you want a portable headphone and can find them on a sale. 

The Fiio E6, in all honesty, fulfilled basically my portable amp needs. It has more voltage output than my portable media players. It fit very nicely in my pocket. From a portable usability standpoint, it was great.
 
My main issues were from attempting to use it as a temporary desktop amp. One thing is that, although it can charge and play at the same time, it was obviously not designed to do so. There would be common high pitched whines in the music when it did this. Furthermore, the battery charges at seemingly random points when it is left plugged in and would wear out the battery over time. Although it was usable as a stopgap desktop amp, it was very poor at doing that job.
 
My other issue is that it was not durable. I'm pretty careful with my audio equipment and my E6 was mostly used in a desktop environment because I wanted a cheap stopgap. At some point in time, the switch to turn it on and toggle the equalizer broke -- it wouldn't toggle anymore, even though it still moved. My E6 was stuck in the off position. I could have opened it up and attempted to fix it, but it didn't really seem worth my time.
 
When my E6 worked, it was good on the go. Just don't expect it to be a good choice in a desktop situation or to have great build quality.

 
Introduction:
I first wrote this review around the end of December 2011. Ever since then, the modded T20RP has become my headphone of choice. I've used them pretty much every day since then. I've added some retrospective comments that around coming around 4 1/2 months after my initial impressions.
 

 
Comfort: The T20RP has a relatively low clamping force with pretty wide pads which fit my ears very snugly. The pads and clamping force didn't bother me, but the headphones were still clamped tight enough to be secure. The headband isn't the most comfortable thing in the world on top of your head, but I don't notice it much. The Fostex headphones, however, were quite heavy -- I suspect they're the heaviest headphone in my collection. Although this didn't both me much, it was certainly different. They're not the most comfortable headphone I've had on my head, but they're certainly comfortable enough have on my head for hours and hours without a break. Overall, they get a four out of five out of me on comfort.
 
After mods, the comfort improved slightly with the most pushed out pads. They did get warm, however, with the better seal and acoustic foam under the pads (acoustic foam converts sound to heat, not sure how much that added, but I seriously doubt it was noticable). As with many pleather pads, when they get warm, they get sweaty, too. That's just problems with pleather in general, though.
 
Comfort Retrospective: I've since modded the headband to be auto-sizing. They are not heavy enough to bother me and I don't notice this anymore.  They are quite comfortable, actually. They're the second most comfortable headphone in my collection, losing out to the one pair of headphones that I use with velour and even less clamping force.
 
Build Quality: The T20RPs felt very ruggedly made. From their replaceable cable to the strong metal build on it to the headband, everything felt like it wasn't going to break and very solid. Pads are quite nice, stitched nicely, and feel comfortable. They're some of the nicer pleather pads I've seen. I felt no need to go out and buy replacement pads from Shure or from an O2 headphone, for what it is worth.
 
Aesthetically, there T20RP brings nothing special. Although Fostex has their own distinct design with their RP headphones, they're no great shakes. It's a kind of boring design that doesn't catch attention.
 
 
 
T20RP Stock Notes:
[Sorry this notes are unorganized, these were just what I was jotting down for the few hours I was testing them stock.]
 
Bass seems really rolled off -- it lets you know that it is there, but does not do much with it.
Mid-bass seems very present -- it's above 70-80hz, though, because the bass drum isn't slamming hard enough to showcase that.
 
Mids sound congested. The mid-bass is definitely leaking into it or something. I'm not sure if it is clear, it just sounds muddied up right now. If you pay close attention, it's definite apparent that the vocals have good microdetails, but it just doesn't sound like it due to the odd tonality of the headphone.
Vocals feel pushed back, as though the singer is singing too far away. I suspect this means that the treble is rolled downward around or before 5khz.
 
Music sounds unnatural, upper-treble seems very rolled off. Cymbals and those types of percussion do not sizzle like they're supposed to sizzle.
Very mediocre PRaT and percussive attack -- suspected roll down of treble at 2khz or below and roll must continue beyond 4khz. You can tell percussion hits, but it just doesn't attack like it is supposed to (especially apparent in Experimental Film by They Might be Giants's opening)
Sibilance suppressed pretty well -- I think this is a trade off for the rest of the treble suppression, though.
Lack of treble makes the music feel veiled.
 
It's like listening to music with the top and bottom chopped off -- not very enjoyable. Definitely a n shaped curve.
 
T20RP Stock + Aggressive Equalization Notes:
 

 
 
Yes, that's a 10dB equalization at 20hz and 20khz. This is probably a bit too aggressive of an equalization, but it certainly improved the sound by a monster degree. I was declaring the Fostex orthos as my personal end-game headphones before even modding them after this. The vocals no longer sound pushed back and you can appreciate the detail the orthos have in the mids. The bass is deep and rumbles very well -- incredible bass extension for $60 and without modding. The heavy mid-bass/lower-mid hump leakage has been entirely eliminated. If modding can improve on this, I'll be incredibly happy with these headphones.
 
T20RP Modded:
Mods implemented: Plasticine mass loading on the driver side, Silverstone acoustic foam lining the opposite site, plasticine mass loaded the headband screw area and placed acoustic foam over it, 2 cotton balls on each ear pad. 3.75 bass ports covered with electrical tape and acoustic foam. Stock earpads with two layers of acoustic foam under the earpads.
 

 
My first impression after I did the first mods was slightly disappointed. I had mass loaded, acoustic foamed, one cotton ball, and 3 bass ports filled. The bass had come out to play, but the highs were massively recessed. I covered half of another bass port and added a cotton ball to each side and that let the highs come back to a level I liked. Sound balance feels very nice, significantly better than stock.
 
The Lows: If one part of the headphone improved the most, the bass would be the area that improved the most from modding. The bass just absolutely jumped out, especially the sub-bass. Very powerful, deep lows. The mod that made the biggest jump after the first mods was adding acoustic foam under the earpads -- I was able to get a significantly better seal with the more puffed out pads, and I think they trapped sound better due to the acoustic damping foam. Originally, I was going to leave a small complaint about the lack of sub-bass, even after my mods, but the superior seal just made the bass hit much better. I'm guessing that pads like the O2 pads give really good or better seals than this and significantly help the low-end.
 
Overall, the bass hits nice and hard. Honestly, after the mods, it's almost too much bass for me, borderline bass heavy but not quite there. The extension is good and the T20RPs sound great for electronic music. At the same time, the bass isn't too slow, it keeps up nicely with Zabava by EnichKin's bass line. Clean, powerful, and deep.
 
My subwoofer mix absolutely rumbles. Trentemoller sounds excellent. The Sleigh Bells' bass slams nicely. The start of Human Rocket by Devo hits hard and jarringly. At the same time, it doesn't threaten the rest of the music by trying to overpower the mids. I love the bass quantity my T20RPs have right now.
 
Lows Retrospective: It's a bit of an exaggeration to call it "very powerful and deep," I think. In fact, most of this section was just hyperbole because I was recently coming from the notoriously bass-light KRK KNS 6400 and any bass at all seemed like a ton. The bass has a solid presence, but it is far from emphasized with my mods -- think of it as deeply extending bass that can hit and slam, but is still underemphasized without EQ. I've since implemented some modestly aggressive bass equalization (it's not as extreme as the previous equalization settings I posted for the stock T20RP), keying up the sub-bass the most. The bass is still definitely clean and quick, though.
 
 
The Mids: Very clean and detailed. The lower mid hump is gone from the sound signature. Vocals no longer feel unnatural or congested. The issue with the singer feeling too far away has been corrected. I haven't done sine wave sweeps, but my gut feeling is that this mod follows the roll-off-after-2khz style of presenting mids and lower treble, because the vocals don't pop out as much. Regardless, the mids on this headphone are the most detailed I've ever heard.
 
Mids Retrospective: I recently did a comparison against the Grados and KRK KNS-6400s I had on hand. At one point in time, I found the KNS-6400s exceptionally clear, but the T20RP modded has dethroned that title. I'm still a big fan of the T20RP's mids, although I have admittedly lowered them a bit with equalization. I did a comparison against my recently arrived Denon AH-D2000's and I found that my $60 Fostex headphones easily outdid them in terms of mids clarity. There was a complete lack of grain in the Fostex that the Denons had in their mids. 
 
The Highs: After mods, they have sufficient volume in the upper highs (12khz+). It can hear the odd high pitched clicking in Holiday by Swimming with Dolphins (as far as I can tell, this sound is centered at 16khz, but extends in both directions, of course), but it isn't overwhelming. I'm admittedly a guy who likes very bright headphones (I love Grados, bump up the treble on my KRKs, Beyers don't bug me, and I rather aggressive equalize Sennheisers) and these are my most subdued headphones of the bunch -- I wouldn't describe them as dark, but they're certainly not bright by my standards, more laidback.  It's a very pleasant, non-fatiguing sound. Overall, the highs are solid and quick. No complaints.
 
Percussive attack is greatly improved. It's not perfect, but it's very good. When you start adding more percussive attack through EQing these headphones, you make sacrifices because the treble and vocals start coming forward more and also run the risk of sibilance.
 
Highs Retrospective: I said no complaints in the review -- this is false. I eventually grew tired of the T20RPs being the most subdued treble headphones in my collection. I've since applied aggressive treble equalization, especially to the upper treble. This is mostly personal preference -- I like very bright, trebly headphones. Pleasant is an okay sound, but I prefer to have emphasized treble. 
 
They still had very rolled off highs after modding, however. 
 
Other Thoughts:
I felt the soundstaging on the T20RP was wider than any of my other closed headphones. It's not quite as wide as a high end open headphone, but it's a very good result for a closed headphone. 
 
Retrospective: 
I dropped the overall sound quality down a click and increased the comfort rating to a 5. I can wear these all day without any problems whatsoever. The lack of upper treble very much annoys me and I heavily EQ up the treble to this day. The Fostex T20RPs are PHENOMENONAL in terms of value and clarity in their price bracket, but I found the quality of their bass to be unable to compete with other mid-fi headphones and their treble extension is subpar. That said, they really shouldn't be competing with mid-fi headphones -- those cost 4 to 10 times more than the T20RPs! The fact that they have cleaner mids is astounding. 

I'm going to level with you -- I bought these headphones for a reason that probably nobody in history has ever purchase the KRK KNS 6400s. I bought them because I thought I might be able to coax a good bass response out of them. I saw the graphs at HeadRoom and InnerFidelity and thought: "These things have the most extended bass response I've seen out of anything in its price range! Only a modded T50RP has that kind of extension under $100! They're underemphasized, but that can be equalized!" Their drivers looked to me like they had the potential to produce a strong bass, along side their excellent mids. It looked like a complete bargain. Thus, I put down the money to buy the KRK KNS 6400s.
 
Build Quality:
 
Simply put, these headphones are built very well. The whole frame feels strong and the headband has a strong piece of metal on it. The cable is detachable and feels like it isn't the type of cable that would break easily. Of every pair of headphones I own, these are the ones I would trust to last the longest physically. I'd feel very comfortable using these as portables due to both their decent size and durability.
 
I found the clamping force to be a bit high at first, but overall they're quite comfortable. They're a bit higher than I'm used to, but it's certainly not prohibitive. As far as the pads go, they're well filled out but still leatherette. I would have liked another option like velour pads, but, as far as pleather goes, they're quite nice and they don't heat up my ears. I can use these headphones for hours at a time and not feel uncomfortable.
 
 
Sound Quality:
 
Of course, the most important part of the headphone is how it actually sounds. I'll break this section up into the highs, the mids, and the lows. I tested these headphones with a Pro-Ject Head Box MK II amp and noticed no obvious differences between them being amped and not.
 
Overall, the sound staging felt above average for a closed pair of headphones.
 
tl;dr: The highs are well-defined with a few minor issues that were probably just me being use to overly bright headphones.
The mids are beautiful, but a little cold.
The bass is very recessed at stock, but improves significantly after EQ. It still lacks some impact, though.
 
Highs: The highs were crisp and quick. One thing I did notice was that the KRKs almost did seem to render the hi-hats with a lack of fullness or something of that sort. It sounded slightly off, but not necessarily bad, just a little different than I was used to hearing. Overall I found the highs to be well defined, but a little duller and laid-back than I am used to. There was no sibilance or any other major problems with the highs. Warning: I am coming to these after mostly using Grado SR80is and Superlux HD-681s, two notoriously bright headphones. It's entirely possible that my ears are just used to bright, fatiguing headphones.
 
Mids: The mids are very beautiful and neutral. The vocals come out more clear on these headphones than I've heard on any closed headphone under $200. Overall, I'd say they're slightly forward but overall very nice.  Switching to any of my lower-end cans makes me immediately miss the detailed mids that the KRKs are able to pull out of the music. In terms of musicality, I feel like these still hold very analytical studio monitor sound -- clear, but not necessarily "fun" or "musical." Regardless, I have almost nothing but praise for the mids on these headphones.
 
Lows: I first tried these headphones as stock and I felt like the music was just missing the basis that held it all together. Even though I enjoyed their overall clarity, their stock bass felt so shy and polite that it really made them one of my less favorite headphones. They certainly could hit low frequencies and noticeably rumble at frequencies even in the 25-30hz range during frequency sweeps, better than some of my other dynamic headphones, but they never really came out to play that much in actual music listening. When I was actually listening to music, the bass was there, but it didn't like to make itself known. Compared to the last headphone I had been using, the Grado SR80is, their bass impact was very lacking.
 
 
 
Now, these are not finalized EQ settings and I have only really been actively working on them for about 1-2 days, but I've gotten some pretty good returns on it. I increased the bass and sub-bass while adding a small mid-bass hump and receded the mids a bit. After I EQ'd up the frequencies around the 65hz region and some of the other bass and sub-bass regions I felt like the cans became much more musical. The music began much more full and less thin sounding. At the same time, it wasn't quite perfect. The bass impact had improved but was still a little lacking, even though the volume was there. Still, there was a definite improvement and made the quite musical.
 
 
 
Personally, I found the graphs at Inner Fidelity and HeadRoom to be accurate, but they were simply not showing one fact -- the KRK KNS 6400 sounds like it has overdamped bass. Overdamped bass just does not get the same impact that normal bass responses can and are more subdued overall, even at the same volume. This, combined with the already recessed bass tuning, resulted in a very bass-shy sounding headphone. This is also why I wasn't able to completely EQ away all of the bass shy factors.
 
Conclusion:
 
The KRK KNS 6400s are a very clear, detailed headphone that I feel is really underrated at Head-Fi. I wouldn't agree fully with MalVeauX and call them "murderously detailed and unforgiving" but they are definitely analytical at heart. To be fair, they were very unmusical to my ears on first impression until I really started playing around with the EQ settings. Still, with a little bit of time working with them, I found them ultimately a surprisingly musical headphone that was less cold than my first impression. For me, they ultimately had no fatal sonic flaws -- I loved the mids, the highs seemed clear and detailed, and the lows were adequate, but not exceptional, after EQ. I give them a guarded recommendation for the detail lover if you're against EQing, but I give them a definite thumbs up at the $80 price point if you're willing to play around with the bass. 
                                                                                                                                         
 
Retrospective:
 

I returned to the KRK KNS 6400s which I so lovingly used as my main headphones for several months and eventually dropped when I received my T20RP -- amusingly enough, I did get a T50RP derivative to get the bass extension I wanted and noted in the introduction to this review. I've grown to adopt the more typical headphone roll-off of the 2khz upper mids/lower treble region. My original equalization made them sound very thin compared to what I was used to hearing now. 
 
Now that I actually have a better DAC than my original headphone out that I was using for the KRKs when I originally wrote the review, I also can appreciate that they were a click more detailed than I original gave them credit. 
 
As for the sound of the headphones, they still retain this level of coldness and a small veil on the highs. I called it "laid-back" in my original review, but I now am hearing it as more of a very slight veil. I said in the original review that it wasn't necessarily worse, but different -- I'd like to revise that to say that I do find it worse. It's not a huge knock against the sound, but it's one regardless.
 
Even playing around with the equalization, the KRK 6400's mids still remain analytic, cold, and removed to an extent. They are definitely bring more clarity than almost anything else in the price range, hands down. Detailed mids are one of the main calling cards of the KRK KNS series. Even with the de-emphasis of the upper mids, though, I still feel like the KRKs are a bit shouty because they jump out forward so much, but that is partially what brings the vocals forward to be analyzed.  
 
I still give the KRK KNS 6400 a thumbs up at its price point.
 
2015 Retrospective:
 
I've since sold the KRK KNS 6400s. I believe that the headphone world has moved on a bit since my first review -- we have much better budget options under $100. I've reduced the rating to 3.5 stars as a result.

Allow me to preface this by saying that I have way more experience with headphones. The only IEMs I've ever owned before this were some cheapie $20 Sony IEMs, the MeElec CW31s, and the MeElect M9-BK. I've sold every IEM I've owned before this one, mostly because I felt like they never got any head time compared to my full-sized cans.
 
The packaging for the 8320 was about was minimalist as you can get -- there were the IEMs with inserts already on, no alternative inserts, no box, just a small plastic bag. 
 
The design felt pretty solid, especially for a headphone of its price. The clothed cable was a nice touch and felt like a definite step up over typical cables for low end earbuds and IEMs, but it did feel cheap. I did find that they very often got tangled. I'm actually very impressed with the durability of the cable so far. I've already accidentally hard slammed the car door on this cable, pulling the Monoprices out of my pocket with such force that one of the tips flew off and they still worked perfectly afterwards.  
 
The comfort could be better, but I'm not a giant fan of cheap IEM comfort. The lack of additional, different sized inserts is somewhat annoying, but they're also $7. The comfort is acceptable, but not something I'd want to wear all day. 
 
As for the sound, the bass is tight and punchy. The sub-bass isn't quite that extended and you get the typical dynamic driver drop-off at the sub-bass frequencies. Bass had a solid amount of impact, but the rumble made bass-heavy electronic music feel a little lacking. Overall, though, I found the bass response to be solid. The mids had a surprising amount of clarity. By no means was it crystal clear, but it was better than I remembered my CW31s. Overall, the details in the mids and highs was solid.
 
For the price, I give the Monoprice 8320s my highest praise. They're certainly not hi-fi audio, but they're absolute monsters in their price range. Most $7 earphones sound and feel like absolute crap, but these could definitely compete with the $20-40 MeElecs. 
 

For a while, I was going out and buying all of the little Flavor of the Month headphones, searching for that actual "giant killer." Some of them I found to be pretty solid, others I was a little disappointed that there was so much hype for them. The one FotM trend that I found the most interesting, though, were the East Asian headphones that copied the designs of other companies and then put out a sound beyond their price -- companies like Superlux and Takstar. What attracted me to the Superlux HD 681s were the measurements that Tyll had on them from Inner Fidelity -- flat response, low price, high value sound. I bought them and they didn't disappoint.
 
The design felt solid, although terrible for portability. I found the auto-size adjusting band to work perfectly. The pleather earpads were big and, although not the most comfortable things ever, I could wear them for hours without hurting my ears, unlike the Grados. 
 
The first thing I noticed was that they didn't sound like $30-40 headphones. Even the better $30-40 headphones sounded like the HTF600 or the HARX-700 -- good, but you could tell there didn't articulate detail as well as $80-100 headphones, as to be expected. I felt like they were able to resolve details as well as, or maybe even slightly better than my Koss DJ100s. They didn't have a super slow sound like my HTF600s. There was a definite brightness in the upper treble, but besides that they were excellent.
 
The bass was big, relatively tight, and full sounding with good impact. It was quick enough to keep up with songs like the Dark Psytrance song Zabava's bass line without muddying it up. The bass felt like it leaked very slightly into the mids, but a small EQ down at 100hz cleared it up nicely. I loved the quantity of the bass and I felt like it was slightly emphasized but not so much so that it was overpowering. The bass extension was above average for the price, but certainly not up to spec with higher end monitor headphones that have great bass extension. 
 
The mids came out astoundingly clear for the price. Vocals are well done and crisp. Not too much I can say about this -- I found the mids to be very pleasing.
 
The treble is the only area I took found an issue with when it came to sound. The treble definitely had some kind of bright spike to it. It brought up some unusual high frequency artifacts in some songs. Still, with a little EQ work, the piercing brightness faded.
 
Overall I found these headphones to be astounding for the price and are some that I would suggest to anyone who is fine with a semi-open design at the price point. Superlux really delivered a winner that was able to punch out of its price bracket in terms of sound quality. I'm intending to borrow a friend's Audio-Technica M50 to do some A/B testing later, because I legitimately think the Superluxes can compete against them. Are they "giant killers?" Probably not, but they certainly destroy other $30-40 FotM cans in terms of sound quality.
 

When I first put on the XB500s, I have to say, I was rather impressed by how they felt. The giant pillow pads gave a unique feeling that was far different than typical pleather pads in this price range. My main issue came when I began to actually listen to them. I did notice that the overall build quality felt a little spotty and I worried that I would break them with a relatively minor mistake. The volume was high coming even out of a portable source, so amps are unnecessary.
 
In their field of expertise, bass-heavy music, I felt like they did an acceptable job. The bass was incredibly overpowering, but it felt fitting. I had never had a pair of headphones produce that kind of rumble before, the sub-bass was excellent and the bass was all around very tight and well done. My main problem was that they sounded mediocre at best in genres out of their comfort zone. For much more lighter acoustic music or classical the bass shows up all over the place in areas it shouldn't and simply distorts the sound to no longer being fun to listen to. For an idea of how much bass and rumble these things bring, I can EQ down the bass 10dB and they still slam harder than some of my headphones. The mids and highs on these headphones really are not there.
 
That said, they do respond well to equalization. I feel like the reason they respond so well to equalization isn't some innate characteristic of the headphone driver being very adaptable as much as the headphones are already so imbalanced that balancing them out improves them all-around. The sound really clears up if the 100hz range is brought down compared to the mids and highs. Even after this improvement, however, the mids and highs still felt like they were veiled.
 
I feel like the XB500s could be a competitive headphone in the $30-40 range, fighting against cans like the JVC HARX700 and HTF600, but they are a bit outclassed in the $50 range for most general usage. For someone who is a total basshead and wants bass at the sacrifice of all else, I suggest the XB500s. Otherwise, I feel like many other less headphones in the price range offer a greater amount of clarity, sound quality, and build quality. 

Like tdockweiler, I'm a fan of forward mids and these definitely bring it. They are excellent for vocals in general, not just for male vocals. They're relatively neutral sounding with a tight, controlled bass that doesn't extend too low. They're far from being "extreme bass" DJ headphones and I wouldn't suggest them to someone who is a fan of real bass heavy electronic music -- I hardly noticed the subbass on these headphones, even when equalizing it up. It is present, but not thumping like I would want for that type of music. One issue I noticed was that if you didn't take the time to get a proper seal, it completely ruined the bass. The DJ 100s were very dependent on being placed correctly on the head to get any bass impact at all.
 
I loved the build quality on them -- they were comfortably portable and felt very rugged. Most of the design was very sturdy with the housing being metal. The pads, stock, were very shallow and uncomfortable for people with large ears, but were fine for someone like me. I could listen to them for hours without pain, but they were not particularly comfortable. 
 
As for needing an amp, they're fine from a computer audio source, but require amping when coming from a portable source. A Fiio E5 or Fiio E6 is sufficient. 
 
Retrospective:  I take back the amp aspect. It really doesn't make much of a difference if you can hit a high enough volume.

I decided to purchase these headphones after reading the large thread that was praising them greatly. I was in the market for a budget basshead pair of headphones, so it was a logical decision. As soon as I received them, I used them as my primary headphones for a week, while burning them in during the night.
 
My initial impression confirmed that the tone was very warm, musical, and colored. They were pleasant and non-fatiguing to listen to, with a very nice soundstage, and were a massive comfort improvement over my Grados. I did notice a large amount of sound leakage -- it was nothing like a Grado's sound leakage, but it was apparent. These are more semi-closed headphones than they are closed. They felt like an improvement over my more expensive, more analytic cans for genres like electronic. I quickly grew to like them. I compared them against a friend's M50s and decided that, although the M50s had a definite edge, the RP-HTF600s held their ground surprisingly well. I decided I liked the headphones enough to warrant purchasing Pearstone Velour Pads for them. They fit very nicely and improved the comfort to a 5 star rating. 
 
Over time, though, I found myself missing the clarity and punch of my more expensive headphones. By the end of the week, I had switched back to using the Grados as my primary headphones and left the HTF600s as my on-the-go/when-the-Grados-start-feeling-uncomfortable semi-open cans. The best way I can describe how they sounded by comparison is that the HTF600s sounded like they were playing through molasses -- the attack and decay was not very quick. When I played very high-paced bass lines, like those seen in Dark Psytrance music, the HTF600s could barely keep up and the notes were difficult to separate. the more technical features of the headphones were very indicative of their price. The RP-HTF600s are no giant-killers, but they brought a lot of value for the price.
 
Bottom line, for someone looking to try a pair of bassy headphones, these are an excellent starting place. They are easy to drive, forgiving of source, comfortable, and have a musical tone. They offer a high amount of value in the $30-40 price range, but I feel like they begin to start getting outclassed beyond that -- despite the rave reviews of the HTF600, I would not personally buy them again if they are priced outside of that range. I love the returns I got on this headphone for the price, but try to avoid many of the hyperboles offered by the HTF600 fans at Head-Fi. 
 
4/24/12 Retrospective: 
 
These headphones no longer get any head time from me anymore, really. The budget headphone market has expanded since these first became FotMs. I still enjoyed the purchase, but I dropped the value score on this headphone from 4 stars to 3.5 stars and the overall rating from 4 stars to 3.5 stars.
 
Just remember that these are semi-open headphones with some sound leakage and that they are not the absolute highest fidelity for the price. The Monoprice 8323 and the Incipio Forte F38 are, at this time, both technically superior headphones at a lower price.