The M22's do an excellent job. Numerous reviews state that for you to get anything noticably better than the M22's, you'd need to spend significantly more money. You won't be dissapointed with them.
How big is your room?
The HSU STF-2 is an all star performer as a sub. It is, in my opinion, the best bang-for-your buck subwoofer. With music, that is almost undisputed. For movies, a few other subs jump into position but the HSU STF-2 is a very musical sub.
It retails for $400
HSU STF-2
I listen to music in straight stereo mode on my reciever with my M22's and STF-2 and couldn't be happier.
