Sorry, I just had to smile when I saw your post.
A month ago : "I'm just gonna buy some little speakers for my office, let's try these Axioms".
Today : "Not sure my rock-solid 120 W/chan receiver has enough power to get the very best out of these speakers, maybe I should add a separate power amp"
Seriously, my first thought would be that spending $$ on a sub would make you far happier than spending $$ on a new amp. With bookshelf speakers and no sub you tend to turn the volume up higher to get bass... and with a sub you find that you don't need to turn the volume up so much.
I'm not even talking about high-pass filtering the signal going to the M22s yet, which reduces your power requirements even more, just having the sub run "in parallel" with the mains makes a big difference in the way you will listen.
Good luck with whatever you decide.
JB
