Do you already have M80s, PB? Couldn't hurt to try 'em out with a tube amp. Me, I'd probably head more towards a higher powered tube amp (but I know those are godawful expensive). If you keep the volume relatively low, I think you'd be ok.
Having never really heard a tube amp, I can't say whether I'd enjoy the even order distortion. More power to those of you who do! (especially when you admit it's even order distortion...)
I didn't do it, no one saw me, you can't prove anything.