Electrostatics

[Jwg1749]

I take a different view of this. I've had ML Montis for 18 months now. Initially I ran them with a D200. I found the top end really scratchy and the sound generally rather thin: a lot of recordings were simply painful to listen to. I thought the problem might be a lack of power: MLs are known to respond well to very powerful amps, as the impedance is shockingly low at high frequencies.

So I got a D200 Companion on loan, thinking the D400 would do the job. There was no real improvement. At the same time I got a Sanders Magtech on demo. It's a 500W Class A/B power amp that's designed specifically to drive electrostatics. (Sturdy power supply and twenty output stages, which deliver the voltage that ESLs crave.) I found the Magtech superior to the D400 in every way: smoother top end, flatter FR, more holographic soundstage. I bought the Magtech to drive the Montis.

I still have the D200, which drives a pair of Vivid V1.5s in my second system. And I remain a big Devialet fan: I've since bought a pair of Silver Phantoms for the holiday cottage. But I'd advise everyone who owns Martin Logans to try a really beefy amp like the Sanders Magtech. Anyone within reach of west London would be welcome for a comparative demo.

A friend of mine just bought a set of Martin Logans [Ethos] and he has no problems driving them with a Devialet 120. He claims positioning is the key here.
He added a section about Logans in his Devialet review.
I heard the set and it's magical. Not thin or scratchy as you describe the Montis.
Bright, but smooth. Great imaging. Wide soundstage. Warm and deep bass. Nothing wrong with it.

Dev 120/200 review HiFiAdvice [sidenote3]

I suspect the smoother top end your friend has with his Ethos may be connected with the acoustic panels he has behind the speakers (assuming the image on the website you linked to is his set up). It might tame the top end, but this is, of course, not how Martin Logans are designed to be used.

They will sound better if placed in front of a bare wall, so that the rearwards reflection can be heard. This is what they're designed for.

Having heard the two amps side by side, I'm confident your friend would get a better result from the Magtech.

The issues with running electrostatics with Dev amps are well known: see the original Stereophile review of the D-Premier.