i just picked up a yamaha rx 1100u receiver, which supposedly incorporates the mx-600u amp (or its 125w variant). i don't like the dreary black face, but it's an impressive piece nonetheless--as you point out, awesome power, sounds good at low volume. i'd describe the sound as forward and very "solid state"--not quite neutral and transparent--but very listenable. which leads me to conclude that (a) yamaha continued to make good amps in the late 80s (truth be told, this one probably sounds better than the beautiful, classic silver 70s stuff), and (b) amplifier technology really hasn't evolved that much--this unit shows up well against my modern integra/onkyo gear.
