The Amps and Speakers:
Speakers are GR Research Paradox 3's. They're splayed way in, because the room is only 13 feet long. -My listening position is only from 7-10 feet away, and the sharp splaying 'blends' the sound into a continuous wide soundstage (on most recordings) so that the position of the speakers is indiscernible: It dosen't sound like the music is coming from two separate speakers. If you close your eyes and listen, you can't tell where the speakers are.
The wall behind the speakers is covered with high density fiberglass (which is covered with 1 mil plastic), and also the ceiling and walls beside them, for the front 1/3 of the room (4 feet). This absorbs 'early reflections' of sound from behind & beside the speakers. Early reflections really mess up the clarity and imaging, as a result of phase cancellation and comb filtering effects, and also 'tell your brain' that your in a small room. Absorbing early reflections (those that occur within about 20 milliseconds of the original sound) makes a dramatic improvement in sound.
Also, as the room is only about 13 feet long, 9-1/2 feet wide, and 8 feet tall, there is a fair amount of bass resonance in the range of 40-70 Hz. I could improve this by using 'bass traps' (like Helmholz resonators, or 'tube traps'), but I haven't gotten around to doing it yet. Anyway; the next pair of amps I build will be set up in the (much larger) living room that has less of a resonance problem.