Agreed, SQ driving an easy (8 ohm) stereo load should be pretty uniform. I think in an A/B/C test, the preference often will go to the unit that happens to be set very slightly louder. The listener might not be able to rank them by volume, but the effect can still be there. Choosing by features and price is reasonable.
I too have seen notes of the effects of room character, with perhaps advice to do "acoustic treatments" but very little indication of how to assess a room and what to do about it once one does.
