My suggestion would be to purchase the M22's. I have made a comparison between them and the M40's, and I found the M22's to be a more complete speaker, if coupled with a subwoofer. The M40's reminded me of M3's that reach the floor. They have a laid back midrange, and their bass extension is slightly more than the M22's.
The M22's offer more detail, soundstage, clarity, and openess. Their response is extremely flat. They also play slightly louder than the M40's, believe it or not.
You can read reviews at www.audioreview.com to see what non-Axiom board members have to say about these speakers.
