I lived in a 700 sq. ft apartment with full walls and wall to wall carpet. Now the place I'm in now is 900 sq ft. with 13 foot ceilings, a partial wall seperating the bedroom and bathroon and a concrete floor. I was actually surprised to find out that even with the concrete floor the speakers don't seem to bright at all, I haven't tweaked my settings on the receiver yet b/c I still haven't found my setup mic. I have noticed that I need to turn it up alot more to acheive the same volume level, I expected that, but didn't realize how much more it was going to be needed.
My TV also looks small on that really tall wall , I'm so tempted to make the jump to a projector and retire the TV to the bedroom, we'll see...