[satwilson]

  I'm just getting back into High End and pulled my old ESP-950's out of the closet. I was curious what DACS everyone is using with these headphones and what is a good match. I'm looking to spend $1000-$2000 but have decided to wait until after RMAF to see if any new ones are announced.

I have an older pair and use the Audio GD NFB-12 DAC/AMP combo. It is an excellent entry level DAC with dual Wolfson WM8741 DACS, discrete analog stage output. I don't personally believe you have to spend $1-2K to really enjoy them, however if you have the money, go for it. I just got done reading this thread completely and have a few recommendations. I have owned mine for 3 years, bought them used, about 12 years old, SN10227. Some of these ideas have been mentioned before but I thought a recap might be helpful. After corresponding with Kevin Gilmore an upgraded regulated power supply, 3-5A gives some improvement over the stock wall wart. He also felt their wasn't much to be gained from cap upgrades, etc. I have found the most dramatic improvement in sound to be the input signal. Stock line out, 2v, from my NFB-12 was MUCH improved when I switched to variable out, max5v on the NFB-12. The input sensitivity of the E90 is low and the hotter signal  gives much better bass and overall definition. Also, I set the E90 pot at about 90%, 3 oclock backed off of max, and then control the volume with the NFB-12, much easier than the dual pot on the E90. I have never had any squealing or noise aberrations with my old set. I have always felt these to be outstanding cans and until I read this thread, highly underrated/appreciated. Thanks to all the proponents and their descriptions and comparisons to other cans. My other headphones I enjoy are my modded are my T50RP's, and with these 2 budget overachievers, I am very happy. With a good DAC and input signal I am sure you will enjoy your recently unburied treasure. satwilson   

 

[dirtrat]

Thanks for the reply. I have decided to get the Matrix X-Sabre DAC. It has pretty much everything I want. It's RCA outputs are also a little on the hot side at 2.2 vrms so if what you say is true then it should be a good match for my ESP-950's. I didn't think there were any differences in the ESP-950's due to the age of the headphones or maybe I am misunderstanding you. I bought  mine in the 90's but they have been sent in to Koss 3-4 times over the years for repairs so I doubt I have my original pair since they do substitute the box and phones depending on the problem. I'll let everyone know how good this match is after I get the DAC in. Also I've decided to purchase a dedicated music server. Still trying to decide if I want to get a Mac Mini, build my own, or buy something like the Auraliti PK90.

 

[satwilson]

  Thanks for the reply. I have decided to get the Matrix X-Sabre DAC. It has pretty much everything I want. It's RCA outputs are also a little on the hot side at 2.2 vrms so if what you say is true then it should be a good match for my ESP-950's. I didn't think there were any differences in the ESP-950's due to the age of the headphones or maybe I am misunderstanding you. I bought  mine in the 90's but they have been sent in to Koss 3-4 times over the years for repairs so I doubt I have my original pair since they do substitute the box and phones depending on the problem. I'll let everyone know how good this match is after I get the DAC in. Also I've decided to purchase a dedicated music server. Still trying to decide if I want to get a Mac Mini, build my own, or buy something like the Auraliti PK90.

dirtrat,
          Welcome, yikes, the Matrix X-Sabre DAC is a great choice. Besides my dual WM8741 DAC I have an ES9023 DAC, which is the budget model of the ES9018 DACS in your Matrix. From my perspective the Sabre DACS offer a little more detail retrieval over the Wolfson but need to be paired with an amp that complements their sound sig. My living room system is all balanced, so the Matrix has been on my radar for a while. The Matrix X Sabre with multiple ES9018 DACS and the XMOS USB, is in my opinion as good as it gets, a bargain for the price. As regards servers, I am using my modded Dell laptop/Winamp/ AGD NFB-12. A budget system that sounds great, and for the ESP 950 headphones sounds great. I still use my Sony ES SACD player in my big system, but am about to go digital server, hence my interest in the Matrix. The Auraliti PK90 should work great via USB>Matrix. I am still trying to decide if my headphone server(Dell, NFB-12) needs to be upgraded for the big system. Isn't bit perfect, bit perfect? I try to save money if I can??? My best friend who has $5000 Sonic Frontiers tube preamps, 4-15" JBL subs, PER SIDE, each sub has its own amp(8 amps for the subs) custom one off ribbon tweeters/focal mids, etc........has decided and purchased the latest Bryston server and DAC for his system. This after we had plugged my headphone server into his big system. His $4000 Bryston rig sounds great, of course better than my headphone server.  Really look forward to your DAC/server upgrade, let us know how it sounds. satwilson

 

[uncola]

+1 for the mac mini, jriver and jremote on ipad

 

[HiFiGuy528]

Here's my unboxing on the current production ESP950.  I'm enjoying it right now and it's amazing.
 

 

[satwilson]

For those interested in a worthwhile upgrade, the 9V, 3A, medical grade(better ground isolation) power supply from Mouser, part# 675-MW173KB0903F01 seems to make a real improvement to me over the stock Koss unit. YMMV. I hear overall a more detailed presentation with better bass. I drive the E90 from the variable output of my headphone amp, AGD NFB12. Set the E90 @ 90% and control volume with the NFB12. BTW the power supply comes without a power cord, so either order one or pull one out of your personal inventory. I would be very interested if anyone else tries this and their impressions. satwilson

 

[Kokomo O]

I'll be curious to read if anyone else tries or has tried the transformer upgrade, and what they think about the sound. It certainly makes sense that it would yield some improvement. I might go out to an electrical supply house at lunchtime that's near a place I've been wanting to try and see if they've got one.
 
Anyone else try the Mouser power supply, or anything similar or even more beefy? One would think the bigger the better.
 
Also, I've been reading through this lengthy thread to see if there's anything I can learn, and it's funny that here's something in the very last post of a 79-page thread. Anyway, I've had my ESP/950s since 1992, and when I got to page 43, where the guy bought a seemingly ancient pair from Amazon with serial number 10193, it impelled me to check my unit's S/N, which is 51005. Then obobskivich reported that he bought his in 2011 and his S/N is in the 90,000s. I'd be curious to know when folks purchased their units and what their S/Ns are--my bet is that Koss made a big production run early, may not have produced any or many since, and is still selling off ESLs from inventory.
 
By the way, I assume by serial number, people mean the number on the back of the E-90. I can't find anything on the headset itself.

 

[DefQon]

A transformer upgrade will not improve sound in a circuit like this period, upgrade and change the amp to something better if you want better sound.

 

[spritzer]

Depending on how tightly regulated the PSU is then it might make a difference simply due to higher output voltage.  There is a lot of bad inside the E/90 and adding another switcher to drive it is not a good call. 

 

[n3rdling]

Anybody have an E90 schematic?

 

[spritzer]

The official one has never been released but Kevin hand drew one 10 years or so ago.  It takes a while to read...

 

[satwilson]

  Anybody have an E90 schematic?

I have asked Kevin Gilmore who has built all the over the top replacement amps for the Stax and Koss stats regarding upgrades to the E90 and his expert opinion was "don't bother", these included cap upgrades, etc. His only suggestion is to upgrade the power supply as I relayed in my post. BTW, I posted this info a while back in this thread. Good luck.

 

[satwilson]

  I'll be curious to read if anyone else tries or has tried the transformer upgrade, and what they think about the sound. It certainly makes sense that it would yield some improvement. I might go out to an electrical supply house at lunchtime that's near a place I've been wanting to try and see if they've got one.
 
Anyone else try the Mouser power supply, or anything similar or even more beefy? One would think the bigger the better.
 
Also, I've been reading through this lengthy thread to see if there's anything I can learn, and it's funny that here's something in the very last post of a 79-page thread. Anyway, I've had my ESP/950s since 1992, and when I got to page 43, where the guy bought a seemingly ancient pair from Amazon with serial number 10193, it impelled me to check my unit's S/N, which is 51005. Then obobskivich reported that he bought his in 2011 and his S/N is in the 90,000s. I'd be curious to know when folks purchased their units and what their S/Ns are--my bet is that Koss made a big production run early, may not have produced any or many since, and is still selling off ESLs from inventory.
 
By the way, I assume by serial number, people mean the number on the back of the E-90. I can't find anything on the headset itself.

What transformer upgrade are you talking about?

 

[DefQon]

I re-read his post and his talking about the wallwart.

 

[satwilson]

  I re-read his post and his talking about the wallwart.

My comments are based on some PM's I exchanged with Kevin specifically regarding E90 upgrades. I am not trying to "expand" on his posts in this thread, just relaying the info he shared with me via  the PM's. If you look at some of my earlier posts you will see me giving credit to him for these ideas.