tube amps and electrostatics

Frogman: "original Quads driven by Levinson ML2 sounded very good."

And what you would have also heard was a more defined and extended treble because those quads and these (ML's Acustats and other els's) go below 1ohm in the treble and start that impedance dip at 10khz.
Tubes I aggree with these speakers still sound good but they are definately subdued in the treble compared to a GOOD s/s amp that is BJT output and that can do current into low impedances. Like you found with the ML2 which can almost keep doubling it's current down to 1ohm for each halving of impedance.

Cheers George

I can't dispute your technical assertions, but I can tell you unequivocally that the electrostats driven by good tube amps that I have heard (my own Stax, Quads/Jadis, Quads/Quicksilver, Soundlab/CJ, and others) have ALL sounded more natural in the highs, and certainly not "deficient" in the highs than even the Quads/Levinson. Your definition of "defined and extended" may not necessarily be my definition of natural.

Atmasphere,
I have a pair of ML Ethos driven by a Plinius SA 201 (class A/B) with an Aesthetix Calypso preamp. They sound great but I would love to get a more natural, more 3D sound. What tube amps would you recommend trying with a pair of zero autoformers?

Frogman: You know I hope that most SS amps have a lower output impedance than most tube amps.

Here is a quote from Roger Sanders of ESL fame a white paper on Solid State v Tubes for ESL's.

"This impedance problem is relatively minor when dealing with conventional, magnetic speakers. But an electrostatic speaker is an entirely different animal. An ESL is a capacitor, not a resistor like a magnetic speaker. The impedance of a capacitor is inversely proportional to frequency. Therefore the impedance of an ESL typically varies from around 150 ohms in the midrange to about 1 ohm at 20 KHz.
A tube amp will be able to drive the high impedance frequency bandwidth (the midrange and lower highs) of an ESL with linear frequency response. However, at higher frequencies, the impedance of the ESL will drop below the impedance of the amplifier and the amp will then roll off the highs to some degree depending on the exact impedance mismatch and the frequencies involved.
I think you can now see why I prefer very high power, solid state amps without any protective circuitry for driving ESLs. This is because they can drive ESLs with linear frequency response, while tube amps roll off the highs."

You can read the whole White Paper here:
http://sanderssoundsystems.com/technical-white-papers/172-tubes-vs-transistors

Cheers George

Ive heard quad esl of cj tube amp. Very nice match!