Thanks for your advice, will look out for a good deal on those, probably leaning closer towards the 717 since you said it's a warmer sound, but hopefully not enough to make it dark or lacking detail with the L300 L.E.'s (limited edition)? And can you explain what you mean by 'diffused' (not a common term I guess)? And did you mean the feedback mod may only be useful on the likes of SR-007 - or may it have any good effect on these Lambda's too? The initial rig I heard the L300 L.E.'s on was the newer Stax SRM-D50 energiser and I was actually quite impressed, liking the sound much better than with my SRM-1 MKII. Am I correct in assuming the 717 or 727II are received as being even better than the D50?
Yes, there amps should be a good improvement over the D50 and are good until you go to the DIY route, which lift up the constraints of Stax amps (a more compact footprint, lower power consumption, readily available mass-market parts, etc.).
Check out this review to have a better idea:
https://positive-feedback.com/Issue12/staxomega.htm
And here is another opinion:
https://www.head-fi.org/threads/the-stax-thread-new.223263/page-670#post-5448390
Here is another one:
https://www.stereophile.com/content/stax-sr-007-omega-ii-electrostatic-headphones-page-3
As you can see there is a ton of information but because the sum of all Stax threads are like several thousand pages long, it needs some digging up. Although interestingly if you scroll down just a little, you can see another different opinion on it, it is always going to be subjective and the KGSS was the original version, there has been a lot of revisions since then (although the pricing has gone to very high levels as well, in the past, even an old Blue Hawaii wasn't that much more expensive than a Stax amps).
In my experience, the modified SRM-727II is a little tighter, more controlled (less midbass) and better separated than the SRM-717.
But I would like to emphasise that the two are
very similar after modding, just a
slight bit more refined, neutral-warm, where the highs gently start to rub off a little. It is the extreme frequencies where the limitations of Stax amps are most apparent.
What I mean that the SRM-727II becomes more linear after the mod, in theory it is not good to have the it without global feedback, but in practise it may not sound bad with certain headphones. It is a an odd design choice that may work for some people.
By the way, I also have the SRM-T1S here (not modded) and it is even more open and warmer than the SRM-727
It is more impressive when you compare the two amplifiers side-by-side because the midrange is sweeter, the sound is warmer, more relaxed (there is added tube bloom to the bass which makes it better at lower volumes) and it has a more open space.
However, there are some things with the solid-state amps that grows on you over time (it is flatter but cleaner, more dynamic and it has a blacker background)
I think people's opinions may heavily differ when they are switching between headphones, amps or DACs, "vigorously" looking for differences between them, compared to just listening to a particular setup for a long period of time, living with that kind of sound, and evaluate it from that point-of-view. A headphone meet where you have noise (which I think is a very big distraction) and an ever shorter amount of time is an even more extreme example.