So here is a somewhat out of left field, eccentric suggestion: original Quad electrostatics refurbished by Electrostatic Solutions (Kent McCollum). He uses thinner diaphragm material and gets better HF response and higher SPL levels compared to the originals.
Advantages:
THE classic speaker: Hi Fi News and Record Reviews Greatest Component of the 20th century.
They are superbly detailed at lower SPLs, and the refurbished versions can play louder than original Quads
One of the, if not THE best midranges ever, even by modern standards
One of the best amp matches is the relatively inexpensive Rogue Audio Atlas Magnum (per Robin Wyatt of Robyatt Audio, who tried out two dozen amps back around 2006 along with David Chesky and Gary Krakow, reported in Planar Speaker Asylum).
Disadvantages:
Not for live rock levels (but those levels can also cause permanent hearing loss). Your room is somewhat large for the Quads but there is nothing that says you can't sit relatively close (6-8 feet away) and that should minimize room effects as the direct sound should predominate. Put them a third of the way into the room and fiddle around a bit for the best location.
No low bass - but good to about 45-50 Hz. Ken Kessler of Hi Fi News was mightily impressed by David Chesky's McCollum upgraded Quads playing bass heavy reggae at levels he associated more with Wilson Alexandrias and such larger speakers.
Limited dispersion, best for a single listener, someone compared them to giant headphones.
