I can answer this thread with a bit of experience. I own a pair of StaxF83 speakers, extremely inefficient electrostatics with very high impedance through most of the midrange. These speakers
are notoriously difficult to drive and are often referred to as "amp killers." The very first amplifiers I tried with them were the Counterpoint SA4. They went into oscillation; which the dealer was able
to fix but I took against it nonetheless. I tried many other amplifiers, including some famous solid state amps and very famous transformer coupled tube amps. Nothing really sounded good until I got a pair
of NYAL Futterman OTL3', which turn out to have a wonderful synergy with these speakers. I have had these speakers and amps for over thirty years now. It has not been entirely trouble free: indeed one amplifier
did catch fire, and the speakers' had to rebuilt after twenty years. But the amplifiers were repaired successfully, and have been re-tubed only once since then. They do not run hot at all, the balance
and bias seem stable, and I still think they sound glorious. Roger Modjeski looked them over recently; said the caps are still fine, and did the re-tubing of one the amps, saying the other did not need it.
Life is complicated.