Just read this from a manufacturer of electrostatic speakers and was curious if CIA amps (past or present) exhibit any problems with this type of driver:
"Some electrostatic speakers have very high capacitance. This raises the potential for three types of undesirable amplifier interaction:
1) All else being equal, the amplifier load from an ESL increases with frequency. High capacitance ESL's will have a very low impedance at high frequencies. When an amplifier that can not drive a low impedance is asked to source a lot of current at high frequencies, the amplifier will limit its output at all frequencies, creating compression, clipping, or some other overload effect.
2) The feedback loops in some amplifiers will not remain stable when driving a large capacitive load. If such an amplifier happens to begin oscillating only when called on to deliver high power, this will cause problems only at high loudness levels. The oscillations may be ultrasonic and thus inaudible, but the indirect, audible effects can include compression, hissing, intermodulation, and chirping, among others. It is also possible to throw an amplifier into an oscillating state called "motorboating", which sounds much like its namesake outboard engine. An amplifier may be harmed while oscillating, or just run warmer than usual.
3) Some switching (e.g., class D) amplifier designs are incompatible with ESL's. If a switching amplifier is designed without enough high frequency feedback, and no special considerations are made in the amplifier for driving ESL's or in the speaker for being driven by switching amplifiers, then the panel capacitance forms a tank with the amplifier's output filter inductance. This will resonate when excited by high frequency signal content, normally at frequencies somewhat but not far above the audio range. It can cause various sorts of distortion, and even arcing of the panels or damage to the amplifier, at sound levels well below the usual limit."