KOSS ESP-950 Thread
Jan 27, 2023 at 9:40 PM Post #4,006 of 4,054
I ordered a regulated power supply to try on the E/90. It is a 72 watt variable voltage 3-12 volts. Initial listening sounds promising
 
Feb 1, 2023 at 9:24 AM Post #4,007 of 4,054
Hello friends, can I ask you a question ? I am looking for a STAX amplifier for EPS950 and my preference is for warm and bassy sound (not bright/clinical) while keeping the price below $1000(new or used).

1) Would something like 323s fit the bill ?
2) How about tube amps like srm-t1 ? Would employing tubes sacrifice the resolution ?
3) Any other considerations ?

Thanks for your help.
 
Feb 1, 2023 at 12:44 PM Post #4,008 of 4,054
I have the SRM 323II, like it better than the Koss amp, but haven't compared it to anything else that can drive the Koss. (and have mostly been listening to various Hifiman planar cans for a while).
 
Feb 1, 2023 at 6:39 PM Post #4,009 of 4,054
@matts19

You are asking for a warm and bassy sound? I doubt you'll find it without tubes and a bunch of money. The closest would be a STAX SRM-T1 but it lacks the bassy I think and it lacks the power to really drive the electrostatic ear speakers. I've owned it and though it sounds great, it was lacking in power. The SRM-T2 would be the better choice IMO and maybe even SRM-006 or 007. Keep in mind, none of these are true tube amps. These are hybrid (tube/solid state).

I would keep an eye on Mjolnir's website because he sells used STAX amps and he always upgrades them. His work is worth the price. Speaking of price, he doesn't make money, you pay him for his parts, and his own money spent.

Just my two cents. I've played with more than a few STAX amps and even had an SRD-7 and in the end, I sold everything off to own one of Mjolnir's built amps.
The problem is, SQ is all up to the listener, you might have to try a few amps out to find that one that sounds sweet to you. Good luck.


/edit I should add that these headphones aren't exactly known for a bassy sound. You might consider some vesper pads. That was one of the biggest upgrades I found with this headphone. Getting a better seal around the ears adds a bit of low end, and doesn't sacrifice the top end.

Mjolnir has a handful of tube STAX amps for sale right now including the below. Prices range from $900 to $1400 USD.

SRM-006tS for sale right now. It's been fully modded.
Price: 1400$ plus shipping
And an SRM-T1 which is a bit unique
Price: 1100$ plus shipping
 
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Feb 1, 2023 at 8:48 PM Post #4,010 of 4,054
Hello friends, can I ask you a question ? I am looking for a STAX amplifier for EPS950 and my preference is for warm and bassy sound (not bright/clinical) while keeping the price below $1000(new or used).

1) Would something like 323s fit the bill ?
2) How about tube amps like srm-t1 ? Would employing tubes sacrifice the resolution ?
3) Any other considerations ?

Thanks for your help.
The 313 and 323 both put out about 350 volt where the E/90 actually swings 1200 volts (not bias which is a fixed 600 volt). Now the 717 and 727 have about 450 volt and if you get one modded by spritzer any of those Stax can get another 20%. If you get an after market regulated power supply, I got a 120 watt variable voltage. Wow more bass control
 
Feb 1, 2023 at 9:07 PM Post #4,012 of 4,054
@matts19

You are asking for a warm and bassy sound? I doubt you'll find it without tubes and a bunch of money. The closest would be a STAX SRM-T1 but it lacks the bassy I think and it lacks the power to really drive the electrostatic ear speakers. I've owned it and though it sounds great, it was lacking in power. The SRM-T2 would be the better choice IMO and maybe even SRM-006 or 007. Keep in mind, none of these are true tube amps. These are hybrid (tube/solid state).

I would keep an eye on Mjolnir's website because he sells used STAX amps and he always upgrades them. His work is worth the price. Speaking of price, he doesn't make money, you pay him for his parts, and his own money spent.

Just my two cents. I've played with more than a few STAX amps and even had an SRD-7 and in the end, I sold everything off to own one of Mjolnir's built amps.
The problem is, SQ is all up to the listener, you might have to try a few amps out to find that one that sounds sweet to you. Good luck.


/edit I should add that these headphones aren't exactly known for a bassy sound. You might consider some vesper pads. That was one of the biggest upgrades I found with this headphone. Getting a better seal around the ears adds a bit of low end, and doesn't sacrifice the top end.

Mjolnir has a handful of tube STAX amps for sale right now including the below. Prices range from $900 to $1400 USD.

SRM-006tS for sale right now. It's been fully modded.
Price: 1400$ plus shipping
And an SRM-T1 which is a bit unique
Price: 1100$ plus shipping
Thanks for the wealth of information. I'm not sure if I want to buy one new, so I will probably scour the Internet and hold out for a reasonably priced used amp.
 
Feb 1, 2023 at 9:38 PM Post #4,013 of 4,054
Feb 1, 2023 at 9:59 PM Post #4,014 of 4,054
He sells used amps. Check his site out if you are serious.

https://mjolnir-audio.com/used-amplifiers/
Wow, this page is amazing. I have to sift through so many choices here and do some due diligence! Also I'll study up on your suggested models. One thing I hadn't mention was that my ESP950 was recently serviced for the squealing drivers and part of the repair was to lower the bias on e/90. Not sure what they did to the drivers though. I hope using one of these STAX amps won't make the issue resurface...
 
Mar 23, 2023 at 4:31 AM Post #4,015 of 4,054
Wow, this page is amazing. I have to sift through so many choices here and do some due diligence! Also I'll study up on your suggested models. One thing I hadn't mention was that my ESP950 was recently serviced for the squealing drivers and part of the repair was to lower the bias on e/90. Not sure what they did to the drivers though. I hope using one of these STAX amps won't make the issue resurface...
I recently purchased one of the cheaper Stax SRM-1 MK 2 units that were listed here - Birgir has a lot of junk laying around so don't be afraid to email him!
After finding a spare Koss cable and converting it to a Koss -> Stax adaptor, I had the unit + cable shipped to me for around $800 AUD. Not a bad price for a refurbished amp that honestly smokes the stock Koss energiser.

Received the ESP-95X back from Koss today; looks like they just replaced the entire unit so I'll be breaking the drivers in from scratch again.
 
Mar 24, 2023 at 9:31 AM Post #4,016 of 4,054
I recently purchased one of the cheaper Stax SRM-1 MK 2 units that were listed here - Birgir has a lot of junk laying around so don't be afraid to email him!
After finding a spare Koss cable and converting it to a Koss -> Stax adaptor, I had the unit + cable shipped to me for around $800 AUD. Not a bad price for a refurbished amp that honestly smokes the stock Koss energiser.

Received the ESP-95X back from Koss today; looks like they just replaced the entire unit so I'll be breaking the drivers in from scratch again.

That page with used Stax looks great, I was thinking of getting a Stax amp and an adapter for my ESP-95X but a friend who is an EE explained that a more powerful amp won't make a different if the 95X isn't designed to draw more power so its basically pointless. I don't know if he is right or not, I'm not an EE, but he said it makes more sense to just buy a full Stax setup then too get an adapter for the 95X.
 
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Mar 24, 2023 at 10:43 AM Post #4,018 of 4,054
@Svperstar I agree with your friend that buying a STAX head-speakers is the way to go but I do own the 95x as well and it does work much better with a quality amp and adapter. Your friend is wrong on that point.

What is the difference exactly?
 
Mar 24, 2023 at 12:45 PM Post #4,019 of 4,054
With the stock amp I felt that it was lacking power. That alone was my biggest complaint about the stock system. With a better amp, the headphones can be driven much better. They get louder and remain clean sounding. With the 95x that was not the case. I also hear more detail due to this.

Once I found a good amp that I liked, I then changed out the pads to Vesper and that again made a nice difference. Then I started thinking about STAX headphones and bought one of those and that is when I realized that the Koss ESP 950 is just an entry level kit. It's good, and can be better with the right equipment but it doesn't touch my STAX cans at all. Its a huge upgrade IMO.
 
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Mar 24, 2023 at 1:15 PM Post #4,020 of 4,054
I haven't tried a Stax amp, so I can't comment on the sonic differences in this particular discussion, but I always find it interesting about people saying the stock amp doesn't go loud enough. Headroom is not an issue I have. I barely turn mine up a quarter turn (about 9 o'clock if it had an indicator) before it gets too loud for me. I guess I just listen quieter than most.
 

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