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Koss PRODJ100: Headphones by which all others must be judged!

post #1 of 22
Thread Starter 

Pros: Tight bass, warm tones, amazing detail, versatility, value, build, comfort, LACK of aural fatigue


Cons: Mild compression, rolled highs, no prestige factor, lack of initial aural “WOW”


I have recently been on an all-consuming quest to find a new set of headphone due to my renewed interest in audiophilia (at least to the extent that I'm willing to take it). Anyways, for the past while I have been intently auditioning several pairs of headphones to replace my aged AKG K240DF (bought in the very late 80s, but just lack the “POW” I want).


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).


So based on internet reviews (and posts on this forum from tdockweiler who is the PRODJ100’s top evangelist) I bought the 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.


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):


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.


Audio-Technica ATH-M50: 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 became too much – it’s almost like they have some kind of built in bass boost chip. 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 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.


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…


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.


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 K240DF, 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 DJ100 – 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.



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 PRODJ100. But in essence the review is that the Koss PRODJ100 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-M50 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 you appreciate their even sonic presentation.


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 K550! Yet at almost 4x the cost, I can say that the K550s only give about 1.25x increase in audio pleasure over the PRODJ100. Think on that before plopping down your hard earned cash.


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 PRODJ100 – and not necessarily for the better. With the ATH-M50 pads the highs on the DJ100 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 DJ100 sounded almost IDENTICAL to the SHR840 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 PRODJ100: their warmth.


So here’s what I suggest: drop $80 on a pair of PRODJ100 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.


(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”)


PRO DJ 100

pro dj 100

Edited by Raeme - 10/25/12 at 7:19pm
post #2 of 22

Nice review and it looks like we MIGHT have a similar preferred signature.

Before the DJ100 I had the SRH-840 and thought it had a near perfect sound signature. Too bad I couldn't deal with it's comfort and was forced to side-grade to the M50.


Unlike you, that thing never WOWed me. It just failed to impress me in any area and I kept it until I had found the K240 Studio and DJ100.

I should note that I had the bass heavy M50 which seemed to lack treble and had recessed mids. Vocals were especially recessed sounding on the M50 I had.

The latest M50 is quite good. Worth maybe $120 or so, but not $160+


The 750 DJ I had seemed very painful to my ears. Too much treble or something. I just know that my ears were in pain. I think it may have needed burn-in.

The SRH-440 was ok based on memory, but since I had the DJ100 I kept that. SRH-440 is quite good for $75 (or whatever it is) but not too comfortable.


I do judge all my new headphone purchases by the DJ100 biggrin.gif Despite being only $80, it holds up well to the other closed headphones i've tried.

I find it better sounding (for my preferences) than the K550, SRH-940 and KRKs.


I still need to try the DT-48E and maybe the MDR F1 (maybe it's good for vocals?)


I remember comparing the DJ100 to the HD-650..I was sitting there and thinking..."this is how much more???". I actually felt my DJ100 sounded better and even more clear/detailed confused_face_2.gif

That was even with an Asgard too.

post #3 of 22
Nice review. I agree on the M50 comparison too - too much boom boom, no good. And heavy. I'd more or less agree with the K550 too - good, but not $300 good. The thing that always gets me about these little Koss 'phones is that I always expect them to sound worse than they do - and I've had them for a while now. Like for example, in reading this review, I decided to pull'em out just for grins. And expected to be greeted with a congested, thin, blurred presentation coming down off the MDR-F1, and instead I get an equally competent presentation, more bass thump, nice mids; very nice indeed (sure, it loses that world-beating soundstage, but c'mon, we're comparing a closed headphone...to the F1!). I like that they always surprise like that. smily_headphones1.gif

And dockweiler - speaking of F1, they're gewd. But they're from another era. Tough to straight-up compare imho, nothing I've heard will compare to their soundstaging (reportedly V1 and K1000 can), the Koss have more bass and midbass, both are relatively warm and n-shaped, the F1 are an extremely open sounding headphone though; they have this quality of "air" that makes most other dynamics sound ham-handed by contrast. The Koss seem to be more "boosted" in the midbass by comparison, and everything sounds richer and heavier - the mids are equally clear, and the treble on both politely rolls down. The Koss are more "in your head" sounding, while the F1 are more "out there in space" sounding. I'd probably give the F1 the nod overall, but it's such a weird comparison imho. We're talking about one of the most open headphones ever designed against a fairly closed headphone. The fact that the Koss can even step into that comparison should tell you everything you need to know about them. ksc75smile.gif
Edited by obobskivich - 10/27/12 at 3:08am
post #4 of 22
Thread Starter 

Hey, guys, thanks for the feedback on the review. Much appreciated. The design of the F1 headphones look really cool.


Since writing I have auditioned both the AKG K240 MKII and the AKG K271 MKII. Out of all the headphone I recently tried, the K240 MKII sounds the best to me (what can I say? obviously my sound preferences haven't changed in all these years since I bought my original pair of K240 DF). I do think the K550 does sound better than the K271 MKII - the K271 just sounds too "hollow" for my liking whereas the K550 are much warmer and impactful. However, the K240 MKII best both of them having a far more richer and dynamic sound - I guess the benefits of having an open design cannot be denied. This goes against my original goal of buying a closed design set of cans for listening in bed - I'm going to keep the PRODJ100 for that purpose and buy a different pair for more private listening.


I just purchased the sApIII SMSL OPA2604 headphone amplifier off of ebay (click here) - this was a bit of a risk because I couldn't find any reviews about this specific product (although other SMSL products seem to be well regarded). So on a whim I bought it and plan to write a full review once I get it. Either it will be boom (haha) or bust and my feeling was to take one for the team because someone needs to review this product. Anyway, I don't want to audition anymore headphones until I have this unit to use for comparison - I also want to see how well it can drive my K240 DFs. BTW, since I first began my headphone quest my old Rotel amplifier has bit the dust; fortunately my CD player has a headphone jack with volume control (it does have the power to drive my K240 DF at about 4/5 volume, but just barely).


Doing some online research, I found out about the AKG K601 (120 ohm) which really looks like an interesting product to me (can be had on Amazon for $199). Do either of you have any experience with these headphones. The other headphones I want to try are the K702 and the Sennheiser HD558 and HD598.


On a final note, I am thinking about buying a second pair of PRODJ100 for modding purposes. I want to try several ideas that I read about here - install the ATH-M50 pads with additional "felt" to soften the bright highs, add fiberfill to increase the sound stage, and then drill a tiny bass port in the cups to see if this warms the sound further with the M50 pads. This is more for fun than anything else.


Comments welcomed!

Edited by Raeme - 10/30/12 at 11:49am
post #5 of 22
I had the K701 (same as 702) and they were nice, I would regard them as better than the DJ100 in staging, extension, and comfort, but they cost a lot more for those improvements, offer no isolation, and are less sensitive. I don't know how the 601 compares.
post #6 of 22
Thread Starter 

Obobskivi, from what I understand, the K601 are very similar in sound to the K701/702 but they are a little warmer (stronger mids) and the highs are a little softer with a slightly smaller sound stage. However, they may be harder to drive since they are 120 ohm and not 55 ohm like the K701. Just wondering, have you ever compared the K701 to the K240 MKII? If so, how much better are they and are they worth the extra cost? For me, design plays a role in the headphones I want to purchase and since I already have the K240DF, buying the K240 MKII (although much easier to drive) doesn't make much sense.

post #7 of 22
I don't remember if I've heard the 240 (yeah...let's just say I haven't), but of the AKGs I can remember, the 701 are the best imho. They're very much a top-tier can imho, but that doesn't mean they're best for everyone or everything. Impedance does not dictate "ease to drive" either. k701smile.gif
post #8 of 22
Originally Posted by Raeme View Post

Obobskivi, from what I understand, the K601 are very similar in sound to the K701/702 but they are a little warmer (stronger mids) and the highs are a little softer with a slightly smaller sound stage. However, they may be harder to drive since they are 120 ohm and not 55 ohm like the K701. Just wondering, have you ever compared the K701 to the K240 MKII? If so, how much better are they and are they worth the extra cost? For me, design plays a role in the headphones I want to purchase and since I already have the K240DF, buying the K240 MKII (although much easier to drive) doesn't make much sense.


The K601 is basically a side-grade to the K702. I prefer the K601 to the K702 by far, but not to the Q701.

The K601 seems slightly warmer than the K702 and has slightly more forward sounding mids. The soundstage is a little smaller, but it does have better imaging than the K702, but I think it's mostly a lot to do with the pads since they aren't angled.


The K601 has less treble, but does seem to have some strange peak in the lower treble perhaps.


The K601 compared to the K702 doesn't seem as clear or as detailed, but it's not a big deal for me.


Another thing is the bass. The Q701 has a little more bass IMO. I thought the K601 might have a bit more mid-bass, but now i'm not so sure...


The K601 has much less mid-bass than the K240 MKII. My K240 MKII seems to have a mid-bass hump sort of, but it's much less bassy than it was straight out of the box. Not sure why.

K240 MKII seems to be close to being dark. Not quite, but compared to the Q701/K702.


I have the K240 Studio right now, but I haven't listened to it in about a year. I need to get it out again!


The K601 is slightly harder to drive than the K701 and Q701. It needs about 10% more volume on my amp. The K400 and K501 are even worse. The K601 is technically supposed to be easier to drive, but it sure doesn't seem like it!


Since the Q701 is now around $235, it's hard to suggest the K601, K702 or K240 Studio anymore over it. The K240 Studio is a steal at $75-$100!


I guess it depends on what kind of sound signature you want..

post #9 of 22
Originally Posted by Raeme View Post


On a final note, I am thinking about buying a second pair of PRODJ100 for modding purposes. I want to try several ideas that I read about here - install the ATH-M50 pads with additional "felt" to soften the bright highs, add fiberfill to increase the sound stage, and then drill a tiny bass port in the cups to see if this warms the sound further with the M50 pads. This is more for fun than anything else.


Comments welcomed!


I never had much luck with modding. It's very, very easy to screw up the sound. Add too  much junk inside the cup and it actually degrades the sound. It seems the most important area are the "ledges" inside the cup and the area behind the driver. It's best to not put anything in these areas. Less is more.


I wouldn't suggest drilling a hole in the cup. It bloats the bass somehow and I regret ever doing this. I only realized this when I drilled holes for a recable.


Even adding some extra dampening material on the back of the driver even changed the sound!


Modding the pads should help a bit. It seems like the more air in between your ear and the driver the more treble you will get.


There's a few threads i've made with the results of my mod testing. In the end it felt like a waste of time. It's also very easy to accidentally cut the wires.


For me the best mod would be to retain it's stock signature (with M50 pads) but make it even better.


It seems like blu-tack did seem to improve the bass a bit, but it needs to be paper thin and not placed directly behind the driver. Putting it on the "ledges" also seems to change the sound too much.

post #10 of 22
Thread Starter 

Holy crap!!!!! I just did a mod to the PRODJ100s that really opens up the sound stage and resonance as well as removes some of the "compression" I previously felt existed (mostly on the top end).


If you remove the ear pads you will see three groups of holes (in sets of 6 I think) that are drilled around the perimeter of the driver board. Behind these holes is some kind of tape (it seems thicker than masking tape, but about the same color), well I poked holes through this tape so that the plastic holes were completely open - no tape to block them. Wow, I really heard a difference in the sound: not only in what I mentioned before, but also the imaging is hugely increased. This imaging improvement results in more of a sonic "3D" effect. Just fantastic.


I'll give a good example of sonically where I really heard a difference. On The Beatles "Love" album, at the beginning of "Eleanor Rigby" there is a cello playing (I have used this piece of music as pretty much the first track I listen to when auditioning headphones just to hear that cello). The PRODJ100 has always reproduced this with a very warm, life-like sound (or "timber"), but it has always lacked the resonance that the body of a cello makes (the SHR840 had the exact opposite problem to my ears). With the mod, the cello now has the resonance it should. Also, percussive instruments really become more full bodied and expansive. Again, Ringo's drumming on "A Day in the Life" is much more immersive.


So who else is willing to try this mod and confirm that my ears have not been deceived?


As a footnote, I will say this will not ruin your headphones - the sound improvement isn't so drastic that you'll be like "these are totally different headphones!" Plus, you can always recover the holes if you think I've led you astray...


Let me know!

Edited by Raeme - 10/31/12 at 8:38am
post #11 of 22

After reading your suggestion to poke holes through the tape. I had to give it a try to see if it would improve the sound. Big mistake for me as it took away the smoothness of the instruments, really harsh to my ears. Imaging was more prominent but harsh. Now I'm desperate to duplicate the old sound but masking tape just isn't doing it. Anyone have any suggestions on the sort of tape I need ? Although the M50 pads are a big improvement on the clarity it loses some of the character of the Koss pads. I've put a single sheet of kitchen roll cut to the size of the headphone between the headphone and the pads. To my hears it's now more like the Koss pads but with the comfort of the M50s.  

post #12 of 22
I tried this mod a long time ago and didn't like the results at all. For me it just seemed to make them harsher sounding and with more treble. I believe I was using stock pads but not 100% sure.
I also had an issue with recovering from this mod (years ago).

Bradley, you could try 3M Micropore tape at any Walgreens (it's around $4 I believe, yuck) or some really thin paper towel.

When modding the insides of the headphone I only managed to alter it's sound signature too much. At one point the bass was a bit better, but it seemed to ruin other areas of the sound.

When you mean kitchen roll, do you mean the type that has holes in it? There's a type people use for modding the T50RP.

Right now i'm using Pro700 MKII pads. They're like stock, but sound a bit better. Those with larger ears should avoid them. I think maybe the reason they sound better is that your ears are further away from the driver and you get a tad more treble.

I think tomorrow i'll buy some HDJ-2000 pads and see how those are..$35, so it's a bit risky.

BTW I really do think the pads and these magic holes play a small role in how the DJ100 will sound. I always felt like the DJ100 was about 10-15% better with pad upgrades.

Oh yeah...my suggestion for paper towel is Viva. I mean for fixing those holes. I use this on my KRK KNS-8400.
Edited by tdockweiler - 11/26/12 at 9:16pm
post #13 of 22

I'm glad your trying the Pro700 markII pads, I've been wondering about those for a while now. How do they compare to the M50s and Koss pads for sound and comfort ?


Since making those dame holes I can't listen to anything with to much volume. Thanks for the suggestion on the 3M micropore tape, I just hope it restores the sound signature or a least takes away the harshness. The kitchen roll I've used does not have holes in it, just a thin generic brand. 


Look forward to hearing how you get on with the HDJ-2000 pads.

post #14 of 22

I had previously owned these headphones before and have to say I was surprised at the clarity! The only cons I had was the headphones being scratch prone, sibilant, and having small bass "quantity." But at the time I owned them, I had no knowledge of headphone amps/DAC's and just plugged them into my iphone 4s. How do these sound with a good source/amp/DAC? 

post #15 of 22

  I can only say I love these headphones using them plugged into my Onkyo amp with a equalizer behind it .  As I sit here listening to  Montroses  "Space Station Number 9 " .  This is a sonic experience . These things rock behind a real stereo amp .

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