Good post Peter. I've been lurking since this thread started. Amps are a favourite pastime and I continue to own several solid state and tube amps, much to my wife's chagrin.
The M80s sound terrific with any good capable tube amp. I'm not sure where this notion came that you can only play them with solid state or that somehow tube amps are obsolete. For dedicated stereo usage tube gear really does offer some advantages. But like all audio gear not all tube amps are created equal. I've always liked McIntosh amps and having heard the M80s using an MC2102, MC275 and a pair of old MC30s. All those tube amps add an air of realism to vocals and strings which are hard to reproduce with solid state amps.
The c30s I have to admit are less pleasant sounding since at 30watts they have a tough time powering the woofers, the net result being sluggish sounding bass at louder volumes. On the other hand both the 75wps MC275 and 135wps MC2102 really sound wonderful with that liquid midrange Mac tube gear is noted for.
I've also heard them with Bryston 4Bssts and the 1400-2. Fact is they sound good with most amps as long as they are played without clipping the amp, and perhaps more importantly properly positioned in the room.
