I'm setting up yet another rig for someone. Busy month... In any case, the room is large enough to warrant floorstanders for mains. We're able to obtain either of these for about the same coin. I personally have the MS906 in my main room and think they're great and so does the person in question. However, I can't seem to ignore all the great things people keep saying about av123 speakers and subs. I've only heard the bookshelf models and I agree with what others felt. The bookshelves are a bit boomy when run full range and a bit weak in the high-end, but pretty good overall. I read the audioholics review of the x-mtm and it talks about bass heaviness and weak soundstaging. Opposite of myself who prefers clean, musical bass, the slight boomy bass of the av123 is a plus in this situation, although, the speakers will probably be crossed at about 60-80 anyways. Can anyone compare how the MS and av123 compare in terms of sound?