Truly weird "review" of the Stax SRM-T8000 energiser. See here...
Stax SRM-T8000 Review
He states.
"the T8000 features a pair of 6922 double-triodes in the input stage and a solid-state output stage. This form of hybrid amplifier circuit is commonplace in traditional two-channel amplifiers, but has been harder to utilise in Stax energisers because of the high impedance of an electrostatic transducer."
Huh? There are lots of energisers with solid state output stages.