Used speakers $7,000-$10,000

Dave, you're right.
The SS M9ES speakers were borderline Class A and the SS M9ED are a Class A reference speaker, competitive with the rest of the reasonably priced class A speakers.

Rarely, the OLD, 3 box version of the Audio Physic Caldera comes up used. Phenomenal sound, imo. Within the last few months a pair was for sale on Audiogon for ABOUT 10,000. Audio Physic Avanti III's have been highly praised, but I've not heard them. Would try them out first with the Odyssey Stratos Extreme monoblock amps and Tempest Extreme preamp that I already own.

Tyler Acoustics Woodmere, McIntosh XRT-28, VonSchweikert DB99.

---Dave

From personal experience I won’t give a 2nd or 3rd choice but as a first choice I would consider a pair of Sound Lab full range electrostatics. I have noticed several available recently between 6-10K. Others are in a better position to recommend appropriate amplification but it should act as a good voltage source given the speaker’s high impedance.

Used or new Merlin VSM-MX with SuperBAM+. Among the finest speakers made, easy load for medium-powered tube amp, small footprint, and at the bottom of your price range.

Dave