tube amps and electrostatics

I am presently running audiovalve challenger 180 monoblocks driving soundlab M2's with excellent results.I am able to roll el34,6550 and kt88's with these amps and the results are stellar.

Here are just two speakers that are not a good match with tube amps the Infinity Kappa 9 and an Acoustat not shown is the phase angles which can make them even worse as seen by the amp.
http://www.rageaudio.com.au/index.php?p=1_12

Note the low impedance dips (left scale) at 2ohms and down to .5ohm and at what frequency (across the bottom), this is where tube amps will have trouble. (right scale is the phase in degrees not plotted) when this goes into the minus figure with low impedance together then it can become an amp killer at that frequency.

Like this graph of the the Genesis 5.2
http://www.stereophile.com/content/genesis-advanced-technologies-52-loudspeaker-measurements

And this one of the magico Q5
http://www.stereophile.com/content/magico-q5-loudspeaker-measurements

This one of the Sonus Faber
http://www.stereophile.com/content/sonus-faber-cremona-elipsa-loudspeaker-measurements

Cheers George

Rodman9999, Quad also made ss amps.

Sure(the 303 being the first)- But not until 11 years after Walker demonstrated his first truly full-range electrostatic speaker(in 1956). Around the same time that everyone else(McIntosh, ARC, et al) was bowing to SS and the output power demon.

I will let the more technologically astute (Atmasphere) explain the reasons why, but one of the most eye-opening and educational experiences for me happened about twenty years ago. I bought my first pair of Stax F-81 electrostatics (known to be a highly inefficient and brutal load) after hearing them sound glorious in a friend's system. My amp at the time was a NYAL Moscode 600 capable of 300w at 8ohms and 500w at 4 ohms; it is a hybrid design with ss output stage. I thought, surely the Moscode can drive the Stax with no problems. Wrong! The Moscode sounded thin, flat, and DEAD DEAD DEAD, with no dynamic verve. I tried various cables; no better. Then, for the hell of it, I tried a rusty old Dynaco ST70 (35w) that I had bought at a local TV repair shop for $50 and was my first pure tube amp. I figured, what the hell? Result: MUSIC!! The Stax's suddenly sounded the way I remembered them; sweet, refined, detailed, dimensional, and within an admittedly limited dynamic range, very ALIVE and dynamic. I drive my current Stax's with Manley tube mono's with great results.