I like the fact that Axiom does not try to convince you that you need to get their more expensive products when the M22s are great enough for your room.

I have 16'x13'x9' (1872 cu) and let me tell you the EP500 is LOUD in my room. You could save some $$ if you go with EP400 or even EP350 and I bet they would still rock. But then again, you might want to avoid the "what if" thinking and just go with EP500 right away.