Yes, Chrono, 8 watts is more than enough. I've used a 5 watt per channel SET tubie to drive a pair of M22s, M3s and a pair of M22 like Michaura M55s. I spoke with Joe V at Axiom who said that 5 wpc from a tube amp would be fine.
I spent 3 hours this evening listening to a 5 wpc set up and can tell you that it just doesn't get any better. I listened to a pair of M55s sourced by an upgraded Ah! Njoe Tjoeb tube output CD player upgraded with a pair of Siemens tubes and the upsampler (TjoUpsampler). Loreena McKennett's Elemental, Chris Colangelo's 2 trios + 1 live, and Getz/Jobim on Verve. Couldn't believe my ears.
BTW, for those of you who think that all CD players are the same, do yourselves a favor and track down one of these Ah! CDPs and live a little.
Enjoy the Music. Trust your ears. Laugh at Folks Who Claim to Know it All.