Koss PRODJ100

A bit about myself - I'm a female student from HK studying in the US. I mainly listen to classical, instrumental and pop, and in general I tend to enjoy headphones that are balanced with a touch of warmth. I also value a wide soundstage, accurate positioning, and to a slightly lesser degree clarity and micro-detail retrieval. I should also mention that I'm not very tolerant towards sibilance and shrill treble in general. 

Alternate link: https://girlinaudiophilia.wordpress.com/2016/05/16/thoughts-on-prodj100/

Introduction

The Koss ProDJ100 is a pair of portable, closed, over-ear headphones currently priced at ~$50 on Amazon. They are known (or not) for their good build quality and bang-for-buck. While opinions on them differ on Head-Fi, I decided to give them a try, as well as compare the stock pads to modded HM5 pads. I won't ramble on and on just so you can finish reading this review without me boring you to death and continue with your life!

Setup used:

Portable: Hidizs AP100

Desktop: Macbook Air –> O2 Combo

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Appearance, Build Quality and Comfort

Being a budget-orientated headphone, the packaging is more of the no-frills approach. You get the headphones, a 3.5-6.35mm adapter and that’s it. If they were more expensive headphones I would complain, but for the price I got them there’s nothing to complain about.

I was surprised by the build quality of the these cans and how sleek they look. For under $100, these seem very sturdy. The outer shells are presumably made of aluminum and have a very nice finish to them – I’ve abused them since I bought them, leaving it in my bag without a case, and they’ve held up very well. I think the hinges are also made of metal, so I wouldn’t worry about them breaking on me. The headband, especially, is what I like the most about these headphones. It’s very well padded and sits on my head very comfortably. The one issue I have is the coiled cable – sure, it’s very well made and sturdy, but for portable use I’d like to have something just a bit more portable. Nonetheless, build-quality wise there’s not much to complain – it seems very well-built and probably would be able to withstand some torture.

The pads deserve some mention, and not really for a good reason. Those with large ears will especially feel the pain – the stock pads are extremely shallow and uncomfortable. I had issues wearing them for more than ~2 hours with the stock pads because of the medium clamping force and the fact that my ears were constantly being compressed by the base of the pads. Many people mentioned the M50x pads as an alternative, but personally I have issues with pleather/leather pads of any kind so I bought some HM5 pads and modded them. That solved the comfort issue. After changing pads, these are fairly comfortable, especially with the velour HM5 pads and low clamping force – I can see myself using them on 16-hour plane rides. Although the velour pads somewhat reduces the isolation, the sound leak is still small enough for these to be used in public areas.

Some glory pictures that are not very professional (sorry!)- 



The nice aluminum cups
 


The headband. If they used the same comfort level on the pads I'd be a very happy girl.


Sturdy hinges - more headphone makers need to learn from this

The mono-stereo switch, something I'll probably never use but neat feature anyway

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Sound Quality

For a sub-$100 headphones, these aren’t bad. Changing the pads did alter the sound signature somewhat – however, I would still characterize both configurations as relatively balanced with a slight boost in the mid regions.

First Impressions:

Slightly harsh and tinny on the upper-mid and treble regions with some sibilance and somewhat boosted bass. Not exactly the best first impression, but people did mention something about burning in. The midrange is pretty clear for something of this price, though. Oh well, I guess I’ll let it warm up (literally) for a bit…

Note: I did find the harshness in the treble to soften after burning in. However, I do think that it may be a psychological effect – take this with a grain of salt! 

Treble:

The difference between HM5 pads and stock pads is small enough for me to discuss them together. Although the sibilance I heard out of the box has subsided somewhat, there is still some sharpness and harshness to the treble – by no means unacceptable though. The highs are slightly grainy but pretty detailed.

Mids:

I don’t really know how exactly to describe the mids… Imagine some honey, really thick and luscious. Then dilute it with some of water and sprinkle some table salt on it. Essentially that’s the mids – it’s not exactly thick and luscious, but not really thin either. In my opinion they do shine the most, but that’s also because I listen to a lot of vocal music. The upper mids are especially prominent, making them a good choice for female vocals. For example, listening to this track showcases to which the upper mids stand out – Solji’s voice sounds very vivid and forward. They are really detailed as well, probably the best I've heard since the glory of FLC8S. But then you can't really compare a $300 IEM to a $50 headphone, right? 

Bass:

This is where I felt pad-switching really made a difference. The stock pads made the bass somewhat heavier and there was a noticeable bump in the mid-bass region that I didn’t really like. However, even with the bump, the bass wasn’t overly prominent and was fast enough for the music I listen to. With the modded HM5 pads, it brought the sub-bass further up but pushed the mid-bass down, resulting in a more linear bass response that I liked better and made the mids shine more (which is what I live for anyway – liquid-gold mids!)

Across the spectrum:

This is another place where I found that the pads influenced the sound. With the stock pads, the headphones sound more closed-in – it was a good, well-rounded soundstage for a pair of closed headphones, but I would immediately feel closed-in after listening to open or even semi-open headphones like the HD668B. Switching to the HM5 pads, I didn’t get as good of a seal, so the soundstage got wider and the headphones opened up a bit more. I personally like the space and air of the HM5 pads, but YMMV (of course). Overall, I would characterize these as pretty balanced and neutral headphones that are perhaps slightly mid-centric.

Sources:

These are hella picky. I made the mistake of listening them unamped out of my phone and cringed at 1. the bad quality of the 128kbps mp3 that Spotify kindly provides to poor students like me, 2. the sibilant highs and 3. how closed in everything sounds. These headphones need POWER. Running them out of AP100 was a lot better, they sounded more balanced and less harsh – it was a nice pairing overall. Pairing them with the XDuoo X3 made the sound somewhat warmer and the treble less harsh, but much of the detail was smoothed out so I preferred the detail of AP100 to the smoothness of the X3. Of course, the desktop setting brought the best out of the DJ100 (IMO), providing enough power to drive these. They sound the most balanced from my desktop setup with no frequency overpowering others (which is kind of sad, considering I bought them for portable use…).

Pads(!):

I’ve already discussed the way HM5 pads affected the sound, so this is just on how exactly I “modded” the HM5 pads. Per the DJ100 thread’s instructions, I turned the pads inside out so the pleather backing (on the back of the velour, just between the thin fabric driver protection layer and the cushions) was facing out. I then carefully cut out four small holes (top, bottom, left, right) so that the memory foam inside the pads were exposed. It may be placebo, but I felt like this brought the bass back up a bit and added a bit of warmth to the sound that wouldn’t be present with stock HM5 pads (they did kill the bass and made them so harsh that I would scream).

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Conclusion: 

These are good headphones for the price. Sure, it’s not perfect and I never expected it to be, but it did do the job well. I’m not sure I would recommend them at their MSRP, considering you still need to get pads to bring the best out of them. They aren’t exactly the best at portability and treble quality (IMO), but for the current street price I’d say these are pretty good everyday headphones if you need something to bring around and torture, as they provide a decent all-rounded package.

This is a great inexpensive headphone with one of my favorite sonic signatures. It's one of the few headphones I bought twice when I tried much more expensive headphones being disappointed and realizing what I had lost.
 
One of the things I look for in headphones is how vocals are represented and these probably beat out most 200 dollar headphones in vocals department. But these are not one focus headphones. They're for studio use so they are well balanced everything is tight and well represented. If you're looking for the humming type of bass found in Beats headphones, you won't get them here. If you're looking for crazy sibilant highs that crackle, they were smart about that too, they stop well short of that cliff in fact maybe that's it's hidden flaw.
 
Maybe the mids are slightly more represented over the highs than they should be. Maybe it's human nature to look for flaws in all things. Maybe the Japanese were right. Wabi-sabi. An imperfect rougher sound signature may be more desirable. I don't know but all headphones should start with this level of vocal clarity and build around it. 

I got mine for $35, and I can't figure out why. They sound perfect to me, with forward mids, clear vocals, and bass that thumps, but isn't in your face. Simply put: if you find these for under $80, snatch em up!

Bass: Definitely not an "extreme bass" headphone like the box says. There is a very slight bass tilt. Very tight bass. Very well extended with m50 pads.
Mids: Pretty forward overall. Amazing with vocals. Amazingly smooth mids.
Highs: Has a little bit of treble roll off. Sounds a little thin
The overall clarity and detail is great.
These really work better with an amp. Overall clarity, soundstage, and neutrality improves.
Effects of Ath m50 pad:
Comfort
Bass extension
Tames mids a little (still has forward mids)
Adds a little more depth and a lot of width to soundstage (still nowhere near open headphones of course  )

So, after many many hours of research I finally found a headphone that sounds good and it doesn't go over my limit of $70 in Canada. If I had lived in the U.S. I maybe would have picked up the CAL! instead... but I'm sure glad I didn't! Some impressions:
 
Comfort:
Here's where they fall really short. Comfort. My ears are rather large so the koss sitting on my ears for hours on end (I usually get home, put on my headphones and don't take them off unless I go eat/restroom or go to sleep) gave me some earaches. It wasn't horrible but was uncomfortable nonetheless. However, I've heard that m50 pads enhance them so I decided not to do a review until I get them. Until then I taped my old headphone pads to the koss ones (looked like the most ghetto pads you've ever seen in your life) but were still better than stock. Now that I do have the m50 pads however, the comfort is definitely better than before. The new pads still don't cover my ears fully and just barely touch the bottom part of my ear but their soft texture makes it unnoticeable.
 
Sound:
Sounds excellent but is lacking in bass for me a bit. No worries for me as I've EQ'd it through windows but without EQ the bass is barely noticeable. Yes, it is there, but I want to feel the punch during the bass hits (kinda like how the m50 sounds like). Mids are excellent and the high's are alright. Now I'm no audiophile, but the m50 pads definitely add more treble to the headphones. It was a pretty big difference so I thought of EQing that down to sound like before but after a few minutes I got used to it and appreciated the new clarity and detail in songs now that the treble is a bit higher. Soundstage is great and is even better with the m50's. Highly recommend the dolby headphone trick in foobar to greatly increase soundstage. Search around, you're bound to find it somewhere.
 
Design:
On a white background it kinda looks alright but when I put them on my head, they looked rather good so that's another good point for this headphone. Seems really sturdy and has excellent feel to it.
 
Value:
For $50 it's a steal. I'd still buy it if it was $70. However, I REALLY recommend some m50 pads as it improves soundstage and comfort.
 
The coiled cable does get annoying but I can live with it. Maybe I'll mod it later on to have a removable cable.

Simply put? The lower midrange just isn't there.
 
Everything else, though, is pretty damned nice. Vocals? Clear as hell. Bass? Plenty of impact, and it gets LOW*
 
With that out of the way though, the lower midrange has problems. If I was feeling mean I'd some up with something witty, but **** you.
 
You like powerful vocals, orchestras, or metal? You better start running and screaming. Like R&B? Stick around, these will do you well.
 
*modded with m50 earpads, at least. Without them the midrange changes for the better, but they're otherwise unremarkable, and quite a bit less comfortable.
 
 
 

[size=medium]I have recently been on an all-consuming quest to find a new set of headphone due to my renewed interest in audiophilia. Anyways, for the past while I have been intently auditioning several pairs of headphones to replace my aged AKG K240DFs (bought in the very late 80s, but just lack the “POW” I want).[/size]
 
[size=medium]Just to let you know, my requirements are for a closed design headphone because I often listen music in bed and don’t want to disturb the better half (happy wife, happy life – you married guys know it).[/size]
 
[size=medium]So based on internet reviews (and posts on this forum from tdockweiler who is the PRODJ100’s top evangelist!) I bought the Koss PRODJ100 headphones and was really impressed. But that was not enough – I had to compare these cans to whatever else was out there to make sure my ears didn’t deceived me or that for a few dollars more my audio enjoyment couldn’t be greatly increased.[/size]
 
[size=medium]The PRODJ100 will work with an iPod but just barely at maximum volume. So in order to properly test I broke out my old CD collection, trusty Kenwood DP-5040 disk player and Rotel RA-960BX amplifier (good thing I didn’t follow my wife’s advice and get rid of this equipment) and began my listening. I won’t bore you with all the different tracks I used or the nuances heard per track with each headphone, but here is brief write up on my findings in the order I tried each pair (you’ll note the increase in price):[/size]
 
[size=medium]Shure SRH440: I hated these right out of the gate – the highs were so bright they just hurt my ears! However, after longer listening, I began to appreciate their dynamic range, but overall the sound was lacking and those highs became too fatiguing and unlistenable. Can’t recommend.[/size]
 
[size=medium]Audio-technica ATH-M50s: Talk about “WOW” factor on first listen. These things sound rich, full and dynamic. But after more listening I just found them not to have enough of a balanced signature and the bass just became too much – it’s almost like they have some kind of built in bass boost. I liken them to a really rich tasting pasta dish: the first bite is AMAZING but by the time you get to the end of the meal you feel bloated and you wonder why you just didn’t order the steak. If you have these enjoy! I have a buddy who is very bass centric and I would recommend these headphones in a heartbeat knowing his tastes.[/size]
 
[size=medium]Shure SHRDJ750: Only one word to describe these: boring. I spent the least amount of time listening to these and won’t waste any more time on them. Zzzzzzz…[/size]
 
[size=medium]Shure SHR840: These have what I consider an almost perfect sound signature. Just overall great range, rich/warm texture, tight bass, and definition, definition, definition! But like their little brothers (SHR440) the highs are just a little too high (not as bad) and long listening stints resulted in aural fatigue. Also, for a $200 pair of headphones the build/design is just HORRIBLE – too heavy, what’s with the external wires on the earcups (really?), and just too much plastic. I couldn’t get over the negative qualities, so back they went. If those things don’t bother you, I say get these and you won’t be sorry.[/size]
 
[size=medium]AKG K550: Ok, first off these things should win an industrial design award. My god they are BEAUTIFUL! Sonically they are near perfect – massive sound stage, exacting definition, clear imaging, balanced range (maybe a tich light on the bass, but it is definitely well represented and TIGHT), precise but mellow highs – these are a true reference headphone (it even says so right on them with personality. They aren’t overly warm, but that’s what makes them so exacting in their sound quality (the DJ100 definitely best them for warmth). These remind me a lot of my K240DFs, just with more dynamic range (bass) and much, much better imaging (plus it takes about a third of the power to drive them to awesome volumes). Now these babies cost $300 bucks – almost four times the price of the DJ100s – and in all honesty I just don’t feel they deliver multiple times the audio pleasure! However, I just might keep them (do you believe in love at first sight? First listen?). These actually sound good on the iPod, but like the DJ100s volume has to be set to max. If you’ve got the dough, don’t think twice.[/size]
 
[size=medium]Conclusion[/size]
[size=medium]Ok, so this is hardly an expansive comparison of all makes and models of closed headphones (I hope I wasn’t implying that it was). And maybe it could be said that it is more of a series of mini reviews of the models listed above more so than of the PRODJ100s. But in essence the review is that the PRODJ100s has most of the good qualities of the other headphones and LACKS most of the negatives. However, when you first listen to them you may be disappointed as they don’t have a certain “WOW” factor. But unlike the ATH-M50s which impress from first listen, these things are made for the listening long haul – the more you listen to them the better they get and the more your appreciate their even sonic presentation.[/size]
 
[size=medium]What I think my experience shows is that you don’t have a spend a pile of money to buy a really great pair of headphones. The Koss PRODJ100 are an AMAZING sounding set of cans that you can have for a mere $80. In fact, I would only have a few reservations recommending them over the AKG K550s! Yet, at almost 4x the cost, I can say that the K550s only give about 1.5x increase in audio pleasure over the PRODJ100s. Think on that before plopping down your hard earned cash![/size]
 
[size=medium]I can’t end without discussing the ATH-M50 pad modification that has been suggested by tdockweiler and others. Be warned, this will CHANGE the sound of the PRODJ100s – and not necessarily for the better. With the ATH-M50 pads the highs on the DJ100s definitely open up and they gain much greater definition (they feel more high quality in build too, but that has nothing to do with sound). In fact, with the earpad modification, the DJ100s sounded almost IDENTICAL to the SHR840s in dynamic range and definition (the SHR840 certainly had more “punch” but only by about 15-20%). Truly amazing. But like the SRH840 the highs became fatiguing after a while and the DJ100s definitely lost most of their warmth. In the end to me this is the greatest sonic quality of the PRODJ100s: their warmth.[/size]
 
[size=medium]So here’s what I suggest: drop $80 on a pair of PRODJ100s and use them as a baseline when auditioning new headphones to see if it’s worth it to spend the extra cash. Hell, buy a pair and compare them to your existing cans and see if you didn’t get ripped off! You might just be kicking yourself.[/size]
 
[size=medium](Albums used for testing: The Beatles “Love”, Eels “Daisies of the Galaxy”, Cake “Comfort Eagle”, Groove Collective, “Groove Collective”, The Brand New Heavies “Heavy Rhyme Experience: Vol. 1”, Led Zeppelin “II”, Yes “Close to the Edge”, Duke Ellington “Blues in Orbit”, Regina Spektor “Begin to Hope”)[/size]
 

Well i have some mixed feelings for these headphones. They sound good for the money, but i don't find them very comfotable when have used them for more then a half hour. But let me jump further into the review, and tell you what i think  more specific.
 
Sound quality:
Overall it's good, actually very good for the money you pay. I am reviewing this from my iphone, since they are made for transportable use, and not home listening!
I would say that they ain't natural sounding, but is very well balanced and sounds very dry and crisp. It does not have this deep and smooth base, it's rather very dry, but this is not bad in any way. The bass actually surprised me in any way, because i usually like deep, smooth, soft and round basses, but Koss have done somthing with the bass and it works!!!
The mids are very good for the price, i have never heard mids that good in that price range! It is rich, but sadly  not as powerfull as i would have liked it to be.
The highs are phenomenal, clear and very smooth.
The sound is of course considered after the price!!!!!!!!!!!!!
 
 Sound leak/Isolation:
When you turn the volume up to 7/10 just around there it begins to leak sound, not much but i will begin to leak. I would say that it does a pretty good job, to prevevnt the sound from leaking. And for the isolation, well it's good...... on a scale from 0 to 10 it will get 7,5 and maybe 8. It can be bette, but it does a pretty good job.
 
Build quality and comfort:
The headphones feals a bit flimsy and cheap. But then again i just  throw them down to my bag, and once i sat on them, and they hasn't broken yet. So maybe the are pretty steady.......
The comfort is bad, my ears strats too annoyed after a half hour. And the can have a trend to varm your ears a lot, because the earpads are made out of something very synthetic material.
 
Design:
The look nice when you have them on, actually very nice when you have them on, but otherwise i dosen't think they look good. When they lay on your table, they look very cheap an flimsy!
 
Overall i think they are worth the 90 $ you pay, and remember you get a lifetime warranty from Koss on all their products. And i have tried this warranty, and the service was phenomenal
 
Check out my homepage for pictures...
http://audioheadable.wordpress.com/2012/10/28/koss-dj-100/

So, I bought these after reading a really long thread on the forums along with a new Fiio E7 as suggested, as well as new M50s pads. At first I must say they were pretty terrible and I thought that the people that loved them were retards, but as stated somewhere in that long thread, I've waited for them to burn in (even though I didn't believe that at first). Now, a month later I cannot leave my home without them.

The clarity, the quality and the overall design is just superb. Probably the best paid £50 over a long time. There have been a lot of people that have been complaining how the bass sucks with these, but I truly cannot understand them. They really perform great with bass orientated music.

The thing that most hit me is that they started performing well (at least how I expected them to do) after around 4-5 days from using them constantly, then now I listen again and it feels like it's totally different from before, better in many ways.

Anyways, the design is great, build quality is probably the best you can get at that price tag, sound quality just gets better with time and comfort, well.. With or without the M50s pads it gets sweaty after long listening hours. Though, you only feel that sweat after you take them off, so that's good I guess.

Anyways, looking for something cheap and good? Take em!

These are my first purchase of head-fi recommended headphones. I do not have ANYTHING to compare them to since I'm a novice audio enthusiast. This really amounts to a bit of babbling by someone who does not know very much about his new hobby. However, I will offer my proverbial 2 cents. Here goes nothing:

 

I've had these for about a month and have approximately 40 hours use on them. They may still be burning in at this point.

 

Build Quality: The build quality is quite good for the price point. I think we have all seen the plastic-clad hideousness that sells for 3 or 4 times the price of these. The cups are machined aluminum and most other parts are metal as well. Durability doesn't appear to be a future issue, nor have I read any reports of this being a problem with this model. There's just not a lot of plastic to be found on these.

 

Comfort: The earpads are okay for comfort, but not the best in the heat here in Saigon. I find my ears get quite warm even when I'm in an air-conditioned space. I've read that the pads from Audio Technica M50s are ideal for these - I haven't yet tried that route. I would like to try replacement pads with an oval shape that create a little more space between the ears and the drivers and apparently that's exactly what the M50 pads do, enhancing not only the comfort but the soundstage as well. The cord is a bit heavy, with a good portion of it being coiled. I guess that's part of what makes it DJ-specific. The earcups do swivel around to make it easy for DJs to listen to the room and what they're setting up/mixing on their equipment. That being said, not many people on head-fi buy these for their "DJ-ness." These are good sounding headphones for listening pleasure regardless of the intended target market.

 

Audio Quality: As I've said, I'm a novice here, but we all have to start somewhere. My source is a rockboxed ipod video and I use flac files. With this source and these headphones, the music that sounds best to me is acoustic music, regardless of genre. I've been listening to Fleetwood Mac's Rumors while writing this, and Lindsey Buckingham's guitar sounds fantastic on "Never Going Back Again." The midrange frequencies are pretty forward in these headphones as others have mentioned, but not excessively in performances with acoustic instrumentation. Another album that sounds stellar with these headphones is Tone Poems by David Grisman and Tony Rice. It's all acoustic music being played on fine instruments, and for me, this is where I really enjoy these headphones the most. I do find that there isn't great seperation in amplified music or even in orchestral pieces, especially in the mids. This can be remedied somewhat by tinkering with equalizer settings in Rockbox, but there are limits. I won't say I am put off by this, but there are areas where it doesn't shine as brightly - this is to be expected for this price. As far as the low end is concerned, I think these handle them quite well and I don't get a muddy sound in acoustic instrumentation at all. I don't think they are bass-heavy headphones even though they are marketed as such. To me, they sound fairly neutral in the bass department and do a good overall job with the low end. Once again, with Rockbox, you can tweak it a bit to your liking. A track like "Lush Life" by Johnny Hartman and John Coltrane is a pretty good showcase for the detail it can give in the low end as you listen to Hartman's brilliant baritone. John Coltrane's tenor sax does come out a bit heavy, once again showing a tendency to be mid-forward. A track that reveals some muddiness is "Chubb Sub" by Medeski, Martin, and Wood. It has a bass line that Bootsy Collins would be proud of, but this track reveals some bleeding between instruments/frequencies and general muddiness. If you have a set of cans that are able to handle this track, you will not be disappointed - it's Hammond-organ goodness, a filthy bassline, and syncopated drumming pounding away. The DJ100s come up short with a track like this - it just demands a little too much for these cans to shine in my opinion. That's not to say the experience is ruined, but I can really hear the boundaries imposed by some amped music. Perhaps it has to do with how a track is mixed in the studio...I'm not really sure. There may be albums that are mixed in such a way that sounds terrific with these headphones. My experience has been that amped rock and roll does not allow these headphones to reveal the detail and seperation the way acoustic music does. I do tend to listen to classic rock, so perhaps the recording techniques employed in that era make these headphones work a little harder. A song like "St. Tropez" by Pink Floyd is much better suited for these headphones. The nice seperation is present and the overall quality is more lush and evened out.

 

Final Thoughts: It's awfully difficult to convey such a subjective experience to an audience that is much more experienced than I, perhaps impossible, even. This review may be more instructional for myself than most all readers, as well - I think it's pointing me toward what I'm actually looking for, as well as revealing what I don't want in a set of cans. I think I may in fact be a freak for detail and seperation - that seems to be my bag. I guess that's part of the fun, too - the experience of discovery. The best summary I can give is that, as a new participant in this fantasmagoric hobby, the Koss DJ100s are a very good entry-level set of full-size headphones for a new, budget-conscious hobbyist who wants to dips their toes (and wallet) in the water to see what all the fuss is about, rather than dive in for a set of big boy cans that cost a small fortune. If you find that you're really not all that passionate about the pursuit of hifi bliss after all, than starting out with a pair of these will not leave you with feelings of buyer's remorse - you'll walk away with something you can still enjoy, pass along to a friend or relative who'll enjoy them more, or just sell to somebody else for most of what you paid - I don't think these will depreciate much at all in value. On the other hand, if you're like me, you'll A) be pretty happy with your purchase, B) use these to teach yourself what it is you're really looking for in a set of cans while still enjoying them, and C) surely become quite eager to discover other well-crafted products out there that can bring you ever closer to your ideal music listening experience.

 

 

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've tried about two dozen pairs of headphones and I'm always looking for the absolute best pair for vocals. I also want forward sounding mids, but not too bad. My preference is also for highs that are not harsh or fatiguing. Being somewhat rolled off is ok. I find the SRH-840 is what I like in this area.
 
The best thing about this headphone is the quality of vocals. It just sounds amazing with both male and female vocals. This headphone is absolutely perfect for Jpop, Cantopop, Imogen Heap and Radiohead. The strange thing about this headphone is that the sound feels like an IEM. You feel like you're right there.
 
The highs are somewhat rolled off, but not as badly as the HD-600, but slightly worse then the k240 (55om) and SRH-840. This and the overall sound signature makes them a VERY non fatiguing headphone in every way.
 
Overall, this is a very neutral souding headphone. The only exception is that the mids are slightly forward, but not too badly. About the same as the Grado SR-80 or a tad more.
 
Here's the strange thing. Koss labels them as having "extreme" bass. They sound like they have a lot more bass out of the box, but after burn-in it gets reduced. I don't find these to be bass light or anywhere near that. The bass is VERY well controlled and perhaps people mistake them for being bass light because of this. It has just slightly less bass then my burned in k240 on an amp. Don't buy these if you like a ton of bass. Overall I find they have about the same amount of bass as the SRH-840 or maybe slightly less.
 
Second best thing about these is how natural and accurate everything sounds. Basically, everything sounds pretty similar to what they sound like on my HD-600. These are extremely picky about the source quality. They're VERY revealing of lower bit-rate and poorly mastered CDs. With my HD-600 I feel they can make anything sound good.
 
Soundstage is very good for a closed headphone, but not great. What really impressed me is the imaging of these headphones. I basically feel as if I can pinpoint every single tiny thing. Even more impressive then my HD-600. I think it has to do with the closed design, but i'm not sure. My k240 has fairly poor imaging and that's semi-open. Instrument separation is also very good.
 
The problem with these headphones is that they NEED an amp. I use them with my E5 and Nuforce mobile and they don't sound as good. Despite the low ohm rating I don't suggest them without a GOOD portable amp. I use them with my Total Airhead and they sound great! With a good amp they also have a bit more bass, but not much.
 
Another negative is that my first pair broke due to my own fault. I bought another and they sounded bad out of the box. The mids were very recessed and they just sounded wrong. The mids are nowhere near being recessed normally. I burned them in and after the 1st night they sounded better, but not quite. On the 3rd night they were perfect and just like my last pair. My first pair didn't seem to need burn-in to sound good.
 
I also found out these work with the Pearstone Velour pads. They need to be stretched out though and they look a bit goofy, but not too bad. They're now extremely comfortable. Out of the box I gave the comfort a 7.5/10, but now it's a 9.5/10! Luckily they don't degrade the sound quality.
 
Another nice thing about these is that they're extremely small. I think they're only 6.5oz without the cable. The build quality is also excellent. The cups are 50% metal along with the internal band and one other part.
 
Two other headphones sound very similar in some ways. These sound almost like the Maxell DHP-II, but those are far less neutral and have more bass and mid-bass. The vocals and mids on the DJ100 are far better. The build quality on the DHP-II is also not good. I'm almost positive they share the same drivers or something close. For anyone that cares, Koss has told me that they drivers on the DJ100 are titanium. They're 40mm when I checked my pair.
 
The Koss Pro3aat also sounds similar, but has way too much bass for me and too much clamping force.
 
These headphones are not for everyone. If you focus on vocal quality and good mids, get these. If you want sparkly and very bright highs or massive amounts of bass, look elsewhere. If you love any kind of Jpop or Cantopop, these are an absolute 100% must have. I would also skip these for rap, classical or metal. Classical isn't bad on them. My k240 are far better for classical.
 
My 2nd favorite is the k240 Studio. Those are better for more genres, but the vocals are not as forward and clear. The overall level of detail is also just not as forward. For me, the DJ100's level of detail is a step down from the DT-880 and AD700, but not by much. The mids are like my Grado SR-80 in some ways but without the fatiguing highs (un-modded). The DJ100 has far more bass though, but less mid-bass.
 
So, as you couldn't tell, this is my favorite headphone i've ever owned!

 
I have about 12 hours into this set of phones and I am impressed they do just about everything well not great. I have used them on my PS3 playing BFBC2 and I can hear things I have never heard before. I am able to locate where bullets are coming from and when someone is coming up the stairs. They are not the best for gaming but they will do the trick if you are on a  budget and want something well balanced in all areas. I have tried Rock, Metal, and Rap and the DJ100 seem to take them all really well. I have watched a few Blu-Rays though them too and they seem to do a good job wish there was just a little more bass in them for the explosions and when tanks drive by same when I was playing BFBC2