Hi,
i recently bought a Koss ESP950 system and want to upgrade the amp.I have a tube amp and tube cd-player that are quite good.
So i was wondering is it better for the beginning to buy a Stax amp or energizer to go with my amp because later when i have the time and money to DIY KGSS.

A SRD-7 Mk2 (you need a Pro bias unit) will give you a different flavor then an amp, with more impact and less detail. If you have a good amp then it makes sense to just get an adapter and change little in the system but the problem is finding one. They have been out of production for a long time and are snatched up fairly quickly if they are posted for sale.

The Koss 950 is by general consensus in these forums a very good phone when driven by Stax equipment. That of course means either having the phones recabled a(nd there are people who will do that) or making an adapter.

I made mine by taking one end of the Koss extension cord and soldering the wires to a Stax plug. Another trick I once used successfully when I did not have the plug but did have the right size pins, was to solder the wires to the pins, and insert the pins into a Stax amp (not turned on). To make a solid plug, I wrapped the pins and soldered ends in plastic putty/glue, molded it into a plug shape and let it harden.

An old Stax high bias transformer would probably be a lot cheaper than a Stax amp. Old Stax equipment seems to be undergoing price inflation right now but you may find a reasonably priced older amp. A high powered one like the transistor 717 will still set you back about $1,000.00. It is my understanding that the Stax tube amps won't give you as big voltage swing as the big transistor amps (450v for the 717). There are better tube amps but they are very expensive.

The Koss amp is usable but not a great piece of highfi equipment. Its performance may be improved by getting a beefier 12 volt supply. I used a 5 amp bench power supply for some years amd felt it improved the Koss amp. However I would say that even an old Stax amp such as my SRM3 gives a better result with the 950 phones.

Thank you for your quick replies.
Then i will try to buy a SRD with Pro bias if i have the patience.If not would a SRM-1/MK2
(B series) be a leap foward? One is for sale right now on head-fi.
A new power supply is on the way classic LM723 stabilized 12,6 V ,4A and i will make an adapter from the Koss extension cable and the Stax plug can be found in an electronics shop.I was thinking on recabling the headphones but i am not sure if i void the warranty this way?

Huh i saw now that the amp is sold but there is a C series remaining.
Forgot one thing ,i am moustly interested in stage and detail when i listen to music (rock and jazz mainly)so the SDR would be a nice beginning but in the end i must buy or make a good amp?

Probably "better" to go the energizer route.
Cause its a relative cheap entry, and allows you to safe up for a powerful direct-drive amplifier sometime in the future.

As 'spritzer' say energizers usually give you more impact and less detail than energizers. Its just a matter of taste, and the depth of your pockets.

Spritzer - is there a substantial difference between the sound of the SRD-7 Pro and SRD-7 Mk2? I like my SRM-1 Mk2 Pro just a little better than my SRD-7 Pro with everything except the Senn HE60, which do sound better with the SRD-7 Pro. However, I am only using a Nuforce Icon amp with the SRD-7 Pro, or a Travagans Red with rolled opamps. I almost bought an Almarro A205 Mk2 tube amp for the SRD-7 Pro, but decided on the Woo GES instead since I really wont use it for speakers.

green0153 - I might have a B-series SRM-1 Mk2 Pro for sale soon, since my Woo GES Maxed with pro and normal bias jacks will be built next week (once the case is ready). This amp is fantastic with my ESP950 stax-cabled.

Quote:



The SRM-1 has a different character but it is a very nice amp indeed. I do prefer tube amps like the T1 but it's a personal preference.

Recabling the Koss is a sure way to void the warranty.

Quote:



There is a subtle difference but it is very small. Slightly more detail when compared side by side (both units cleaned with Deoxit/Progold and fresh terminations on the input cables). The amp driving them makes a lot more difference so get a B22...

Quote:



Well, gee if money isn't a concern, why not a Red Wine Audio Signature 30.2 ?? (BTW, have you read the 6moons review on my Nuforce Icon? It's a 12 watt $250 integrated amp that thinks it's a $1000 amp.)

Never mind, my maxed GES will be done in a couple of weeks...

Quote:



Well, I just did... One month ago.
The Red Wine Audio Signature 30.2 is a really great amplifier, which also works like a treat driving Stax'en through an SRD-7 Pro. My next project is to build a higher quality, battery powered, energizer. Should be fun!

Quote:



Perhaps a bunch of us Stax freaks could convince Vinnie from RWA to build some for us. Might be worth a shot.

Great to see the amp has worked out so well for you !

Quote:



I have to admit that thought have struck me. Lets see what happens..

Quote:



Thanks!

Quote:



I've never heard the RWA but going on specs alone and the design I would much rather have the B22 out of those two. A B24 or some Pass Class A amp would also be high on the list.

The Icon might be very good indeed for the price but 6moons is just a huge waste of bandwidth.

Btw. Congrats on the GES.