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Stax SRM-717 vs SRM-727a?

post #1 of 12
Thread Starter 

Hi all, I've been doing a lot of searching in Head-Fi and I see a lot of praises for the older Stax SRM-717 over the newer SRM-727a (or SRM-007tA) but I haven't come across any explanation as to why Stax connoisseurs prefer the older SRM-717. I'm looking for a match for the newer SR-009 headphones.


KGSS, BHSE, WES, & A-10 are out of my price range as such I've narrowed down primarily those two Stax amps.


P.S. I don't mean to rush anyone for responses but I'm most likely be making a purchase of one of the other tomorrow especially when one of them is on auction.

post #2 of 12

According to couple reviews posted here including from spritzer (who is extremely knowledgable and owns/has built many different electrostatic amps, BH, KGSS, T2) the Stax Srm-323s is superior to the stock SRM-727a, is very close to the KGSS and will drive both the Sr-009 or the Sr-007 very well. It is only after modification the srm-727a that it becomes the better but I'm not so sure such a margin is as well noted as say something like the BHSE (Vs 323s).


I'm not so sure where the srm-717 fairs in comparison with the sr-009, but with the sr-007 I felt that the KGSS was a significant upgrade ... which leads me to believe the srm-323s is probably a better choice still (as it has been noted to be very close to the KGSS).

post #3 of 12

The SRM323S should be more neutral but that doesn't mean that it should be a better match with the SR009.

In fact the warmer 717 and 727A amps might pair much better with the SR009.

At least visualguy wrote he prefers the 727A over the KGSS and 323S for the SR009.

But of course the source used is another matter and also very important.


All I can say is that the 717 is very nice with the SR009 and much better than the SRM600 Limited which it was compared against and it is hard to say if the 727A with its "interesting" non-feedback output stage but otherwise improved circuit is better or worse (should be an interesting comparison though) but so far both the 717 and 727A are reported to pair well with the SR009.


If the price difference is small the 727A is probably the better buy as it can always be modified to have feedback in the output stage. And from what I gathered, it is possible that Stax designed the SR009 with the 727A in mind.

Edited by padam - 2/12/12 at 5:01pm
post #4 of 12
Thread Starter 
Thx for the response guys. Today I tested the 727a & 323s briefly at the shop for about 20 minutes. Over this past weekend I've also been testing my friend's 007tA.

Either I'm severely influenced by my friend's 007tA or I actually find the 727 warmer than I'm used to. Admittedly I did test the 007tA for the whole weekend vs a quick 20 min test of the 727 in the shop in a mall (i.e. not the most quiet environment in the world).

The 323s is a no go. I found it somewhat veiled in comparison to the 727a.

No chance to test the 717 as that's under online auction.
post #5 of 12

Interesting finds.  I'm actually considering upgrading to an SR-009 soon, and if the 717/727 is similar, or better, in performance to the KGSS, I'd much prefer it as it's quite a bit smaller.

post #6 of 12
Thread Starter 
You have to take what I said with a pinch of salt though cos circumstances beyond my control, I've tested the 007tA under very different environment from the 727a/323s.

I may bring my friend's 007tA to the shop tonight & test it against the 727a under the same environment. Unfortunately I don't have the luxury of bringing the 727a home.

As for the KGSS, I've only -read- on Head-Fi that most audiophiles prefer it to any of the Stax amps (generalization!!). If only the KGSS is priced the same as the SRM's in Japan the way they are in US frown.gif. It'll be a much easier decision.
post #7 of 12

Originally Posted by akwok View Post

Interesting finds.  I'm actually considering upgrading to an SR-009 soon, and if the 717/727 is similar, or better, in performance to the KGSS, I'd much prefer it as it's quite a bit smaller.

The KGSS is superior (because it is bigger the PSU is much better compared to the Stax amps) but it might also be less forgiving with the SR-009.


As I wrote the source also matters a lot and the RME is not very forgiving so it may be somewhat harsh with the SR-009.


All I can say is that DA11 and 717 sounded marvelous with the SR-009 and the SR-007 wasn't as happy with the same setup (it was veiled in comparison and not well controlled in the bass).

post #8 of 12
Thread Starter 

I just picked up the SRM-727a 30 mins ago. I brought my friend's 007tA and tested against the 727a in the same setup/environment. Seems my original comment about the 727a being warmer wasn't accurate. It was only slightly warmer but not as much as I initially thought. The cause was undoubtedly the environment I was testing in.


However what sold me on the 727a in the end was I found the 007tA somewhat "slow" for some more modern pop/hip-hop music. At least in my opinion, that's where the 727a faired better. Whereas where the 007tA did shine was with Vocal Jazz, West Coast Jazz, and Classical. However the 727a wasn't that far behind the 007tA for Jazz/Classical. So in the end, the 727a to me was the preferred "overall" amp.


Another reason of choosing this 727a over the available-for-purchase 007tA is that the 007tA is on online auction. As my colleague cautioned me, there's no guarantee on the conditions of it tubes.


This will have to be my setup for awhile now to keep the Mrs happy. May a KGSS, WES or BHSE never cross my path....


@padam, funny you mentioned DA11 as at home, that was what I was testing with the 007tA. In the shop though I was testing with a iPhone 4S (Flac Player) -> CLAS (coax) -> Nmode X-DP1-HF.

post #9 of 12
Sorry to invade this topic, but does anyone know inform the technical specifications of the fuses installed in an amplifier STAX SRM-727A (100V)?
Think about replacing them with better quality fuses (Hifi Tuning Supreme).
thank you
post #10 of 12

 The output fuses -high voltage- at back-RHS are -100 MA on a 240V unit.   While the mains input fuse will have a higher value than the UK models the output will not change. 

                The actual current drain is around -60 MA [as tested on mine]  If you change the fuses [which in mine]  are the older long design  keep in mind that the more modern short fuses

                     have a higher series resistance due in part to their short length and that different types are available -surge resistant/quick blow etc and that the working voltage must be taken into  

                       account . Personally I have never had a problem with them other than a couple of times working on the 727-1 / 727-11  I blew them.

                           While silver is a good conductor after a while it tarnishes /gold is not so good as silver but it resists tarnishing / annealed copper is very good

                              The "golden Ears" in the UK advise filing them every so often for better contact .

                                  What I don't like is the cheap PCB clips to hold them in-money saving exercise.

                                     Under a microscope the parallel  connections look bad. where as the modern shorter ones bite sideways [90 degrees] which is MUCH  better[ the connection is a correct


                                                 engineering   job]  If you thought of fitting the short ones buy ONLY the industrial versions-high impact plastic/high quality grip.sockets 

post #11 of 12
Thanks for the information.
I will order the fuses and make the substitution.
Then I come back to report the result.smily_headphones1.gif
post #12 of 12

Well, I came back to tell about replacement of original fuses by HiFi Tuning Supreme. 


What I can say is that the sound was fantastic! It was a nice upgrade. 


I am very happy!: Atsmile:

Edited by Furlan - 5/26/14 at 9:32pm
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