Hi Peete,
More power is always desirable, but it also depends on how large your room is, how far back you sit and whether you have a subwoofer.
The M22s, which I use with an Axiom EP500 subwoofer, can handle lots of power. I'm driving them with a 20-year-old Yamaha power amplifier that's rated at 200 watts per channel.
If you don't have a subwoofer, I'd get the Yamaha with greater power output. You can boost the bass on the M22s using the bass control, to get a little more oomph in the lower octaves until you acquire a sub. The dual woofer/midranges on the M22 tolerate about 3 dB or a bit more bass boost with ease.
Alan
