One of my friends has a Single ended class A Tron amp which he uses with Avante Garde horns.A single ended class A amp would be stupid to the extreme to use as the main amplification for powering a moderate to low efficiency speaker with traditional passive crossovers.
My Goldmund speakers seem pretty efficient, about 10dB less on the Devialet for the same volume as Wilson Alexas so we gave it a try. I assume the load must have been pretty punishing or the transformer badly impedance matched because it could raise barely a peep out of the Goldmunds.
This was before I got my horns, I haven't tried it with them.
OTOH I have tried the Devialet D-Premier, programmed to its lowest power output, with his Avante Gardes and found a marked increase in clarity and detail over his valve amp, though it could have been a tad louder to explain that. He considers the Devialet too clinical and, in any case, terminally compromised by having any association with digital...