Placement definately can make a big difference. The bass seems a lot louder in our kitchen than a few feet away from the sub! That's what can happen when the waves start bouncing around... (My room is really horrible. It doesn't look like a square, because of the open floor plan design, but I think it is a bit too regular in part of it, and it amplifies certain frequencies.)

I have the sub in the corner which I think is supposed to amplify the bass, but it has been hard finding a location where the bass doesn't get all "sucked out" of the center position.

Gary