built both preamps, power amps and an OTL. High voltages is no limitation.
Looking forward to see the solution of this problem from the ultimates of sound.
A good starting point for anyone interested in building his own ES speaker is Roger R. Sanders book, "The Electrostatic loudspeaker Design Cookbook," Audio Amateur Press. His book does not cover any OTL circuits for use with ES speakers. In fact, in the last chapter where he gives us his wish list direct-drive amplifier for ES, he writes, "For a start an acceptable amplifier can't use vacuum tubes." Still, it is an excellent source for information on the design and principles of ES speakers.
Building an OTL for ES requires lots of real estate, as it requires a set of large output tubes and a large power supply. Still, this path is definitely worth pursuing. I believe you will find that using triodes is the only way to go. I once built a pentode based electrostatic headphone amplifier that greatly impressed me on the test bench with no load, but disappointed me when capacitively loaded. The low rp of the triode make it a much better device to drive capacitance. No matter which circuit topology you choose, build a scaled down version first. For example, if you plan on driving 3,000 pf stators to 2000 volt peaks with 845s, build a scaled down version of the amplifier that can drive 300 pf to 200 volt peaks with a 12BH7s. Once all the bugs are worked out and the circuit is optimized, build the scaled up version. One caveat is that you will probably need much more current delivery ability than you expected.