I for one would love to hear the M80's w/ a tube amp, granted, that amp would have to have a bit of power.

I've used my M22's with a Sophia Baby and some ASL AV25 monoblocks, and the power improvement is noticeable. It's definitely a different sound vs my Pio 45TX. For me, it's a positive difference. I now use Von Schwiekert VR1's w/ the ASLs.

Slightly OT, but I've jury rigged the Sophia to work w/ headphones and it sounds quite good w/ my Grados. Enough that I've decided to keep this as my bedside tube amp.