[FrankCooter]

If you need a Stax type male plug, let me know. I have a few spares. There is no charge. Buy the Koss extension cable and reterminate  it with the "Stax" plug.  $15.00 , 30 minutes , and you're done.
 
The 950's, despite their issues, are one of my favorite headphones. Easily the equal of any of the Stax Lambda series.

 

[Avi]

I tried using the KOSS adapter for a week, and then switching to the Medical 3A supply, and I still cannot hear a difference. I've never had "golden" ears, and being over 40, I know my hearing is starting to lose sensitivity, but I get the same bass impact and soundstage with both, and I'm switching plugs as songs are playing. On the scale of the investment we all make in our music, it's small, so I wouldn't advise against it, but for those of us whose ears aren't of the best quality, this is one data point which may indicate that the difference is too fine for us to perceive. Maybe I'll try again after a few more weeks.
 
What I am perceiving is that I may have sold the Koss short on bass. Low bass is there unquestionably. On tracks intending to show low bass (THX - Ultimate Bass Test, end of "To All the Girls" - Beastie Boys) you will feel the impact. But it doesn't overpower midbass. I feel that I am hearing every note cleanly and clearly without even hints of muddle, and it is easier to focus on just the bass, just the drums, just the melody, just the harmony.
 
Also, it is more sensitive to DR. For songs with a larger dynamic range you do feel the impact (especially common on drum beats which tend to be more powerful than melody where DR exists).
 
Lastly, I'm finding it easier to hear the shortcomings of bad tracks (especially ckipping) with the Koss - they resolve more cleanly, and the crackles of clipping are not hidden by other instruments.
 
I'm just not hearing any significant difference between the default Koss adapter and the medical one.

 

[doctorjazz]

I didn't particularly notice more bass, more that tone color across the board had more "there" there, filled in more, were blanched with the Koss amp (I noticed this right away, my main complaint with the stock, and noticed the improvement in this area with the power supply and cord, actually before I got the cord, not sure if that made any more difference). I just got my adapter cord delivered for the Stax 323 today, try it out when I get home, very curious if and by how much it improves. Stay tuned, same bat time, same bat station...

 

[scottiebabie]

I didn't particularly notice more bass, more that tone color across the board had more "there" there, filled in more, were blanched with the Koss amp (I noticed this right away, my main complaint with the stock, and noticed the improvement in this area with the power supply and cord, actually before I got the cord, not sure if that made any more difference). I just got my adapter cord delivered for the Stax 323 today, try it out when I get home, very curious if and by how much it improves. Stay tuned, same bat time, same bat station...

 
cool! am as thrilled as u to know what differences there will be. hopefully its a .... WOW moment where everything is just better & it's like a new headphone! lols.
 
my kgsshv mite still be a while yet 

 

[Avi]

I didn't particularly notice more bass, more that tone color across the board had more "there" there, filled in more, were blanched with the Koss amp (I noticed this right away, my main complaint with the stock, and noticed the improvement in this area with the power supply and cord, actually before I got the cord, not sure if that made any more difference).

Maybe the components in your E90 exhibit more fluctuation allowing the 3A supply to fill in the gaps? I'm not an electrical engineer, so forgive me if what I just said is patent foolishness . I'm also using a standard power cable (one that Jan Meier sent with the JAZZ amp), not an aftermarket power cable.
 
Looking forward to hearing your next review!

 

[doctorjazz]

Beats me, power supply is one of those things that high end designers do pay much attention to when designing gear, and I remember some really expensive megabuck gear like preamps in the thousands being designed with the power supply as a separate unit from the rest of the component. It doesn't seem far fetched that the feather weight Koss Amp would be not up to snuff in the things that amps need to do (you can tell I'm not an electrical engineer as well...get help at home changing the light bulbs )

 

[doctorjazz]

OK, quick 1st impressions with the cable and the Stax 323...remember, I liked the Koss BEFORE the Stax (but, after the power supply and power cord upgrade). Anyway, once you get to this level, the improvements aren't often day and night changes, but a quick listen did show improvements that will mean I will likely soon store the Koss amp. 1st, while I didn't note it before listening to the amp, there is a layer, sort of an electronic haze, which is gone with the Stax-spaces seem more open, voices seem more natural, that haze again is gone, more fleshed out. I found the bass fine with the Koss after upgrading the power. Soundstage width is about the same, but depth has increased with the Stax. Voices and instruments just seem that more REAL. I'm really curious what happens when you take the amp to much further improvement....(listened to my fall back, know-it-like-the-back-of-my-hand high resolution Grateful Dead American Beauty out of my Pono).

 

[crazychile]

OK, quick 1st impressions with the cable and the Stax 323...remember, I liked the Koss BEFORE the Stax (but, after the power supply and power cord upgrade). Anyway, once you get to this level, the improvements aren't often day and night changes, but a quick listen did show improvements that will mean I will likely soon store the Koss amp. 1st, while I didn't note it before listening to the amp, there is a layer, sort of an electronic haze, which is gone with the Stax-spaces seem more open, voices seem more natural, that haze again is gone, more fleshed out. I found the bass fine with the Koss after upgrading the power. Soundstage width is about the same, but depth has increased with the Stax. Voices and instruments just seem that more REAL. I'm really curious what happens when you take the amp to much further improvement....(listened to my fall back, know-it-like-the-back-of-my-hand high resolution Grateful Dead American Beauty out of my Pono).

Thanks Doc! This was what I was hoping to hear. I get the impression when listening to the Koss'  through the stock amp that there was still a small layer of grunge that could be removed with a better amp, and that's what I am reading in your description also. Please keep us up to date as you have more time to listen.
 
Also, how did the Darin Fong cable work? I thought I had read somewhere that the Stax plug used on that cable wasn't a 100% perfect fit.
 
Thanks!

 

[doctorjazz]

Mine fit perfectly, looks nicely done.

 

[scottiebabie]

  If you need a Stax type male plug, let me know. I have a few spares. There is no charge. Buy the Koss extension cable and reterminate  it with the "Stax" plug.  $15.00 , 30 minutes , and you're done.
 
The 950's, despite their issues, are one of my favorite headphones. Easily the equal of any of the Stax Lambda series.

 
Frank gave me one of his last stax plugs. thanks again for your generosity & contribution to this community!
 

OK, quick 1st impressions with the cable and the Stax 323...remember, I liked the Koss BEFORE the Stax (but, after the power supply and power cord upgrade). Anyway, once you get to this level, the improvements aren't often day and night changes, but a quick listen did show improvements that will mean I will likely soon store the Koss amp. 1st, while I didn't note it before listening to the amp, there is a layer, sort of an electronic haze, which is gone with the Stax-spaces seem more open, voices seem more natural, that haze again is gone, more fleshed out. I found the bass fine with the Koss after upgrading the power. Soundstage width is about the same, but depth has increased with the Stax. Voices and instruments just seem that more REAL. I'm really curious what happens when you take the amp to much further improvement....(listened to my fall back, know-it-like-the-back-of-my-hand high resolution Grateful Dead American Beauty out of my Pono).

 
great! i now have an idea of what to expect when the koss gets fed properly. did u perchance find any changes to the koss's tonality - specifically the elimination of the slight leanness i hear? 

 

[scottiebabie]

probably OT for now but here's pic of the esp950's new amp
 

 
not quite finished but getting there. hope to have it done in the next coupla weeks...touchwood. maybe then i can say, with all sincerity, i love the Koss!

 

[doctorjazz]

Cool, keep us posted.
as for the Stax 323 saga, I wouldn't say tonality has become ric, like, say, the FAD Hope VI, but I'm not hearing the thinness I heard when I first got the Koss, fairly neutral to my ears.

 

[scottiebabie]

Cool, keep us posted.
as for the Stax 323 saga, I wouldn't say tonality has become ric, like, say, the FAD Hope VI, but I'm not hearing the thinness I heard when I first got the Koss, fairly neutral to my ears.

 
nice! exactly what i hope to hear!! the koss's midrange is already sweet so im not looking for more body in that sense. neutral tonality in the vein of a hd600 is what im hoping for. that plus extra bottom/high extension combined with the other positives of the esp950 would make this a keeper.

 

[mrscotchguy]

So I'm still sitting on the borrowed +/-20 year old 950, got some 100% deoxit and cleaned the amp up for my friend, if he ever requests for it back...

Anyway, after some more listening, I have come to the conclusion that the 950 is heavily dac dependent. More so than most of my headphones, maybe even more than my hd800 (maybe...). Feeding the little e90 from my wolfson wm8741 Audio-GD dac, these cans sound super warm. With the Beresford bushmaster, they never did. Soundstage was also congested on the AGD by comparison. But bass was much fuller and buttery.

Ultimately, the dac made these seem almost like different headphones. For my tastes, I would recommend a hyper-detailed, bass-tight dac over the smooth, warm sound of a wolfson 8741 chip.

As always, imho and ymmv...

 

[Sorrodje]

@mrscotchguy : seems legit .  The bushmaster should be a good companion then : Airy, detailed & open.