If we can stay a bit with Yamaha I will sugest the A-2000 (early 80's) witch is a stunning unit, the amp part is a power downgraded B-2x but same design. That alone makes the unit worth seeking out, the bad thing is it was a japan only unit. But still, properly the best integrated Yamaha ever build.
Funny enough, if the A-2000 was not the best integrated from Yamaha. Then it must be the AX-2000a, part of the Titanium series (Yamahas TOTL series from 89-93). Just the weight alone - 28kg, sayes good old traditions.
130W @ 8 ohm (0,003%), dynamic power of 600W @ 1ohm.