I was in an A&B Sound the other day and some sales people where demoing some PSB equipment for a couple, turning the volume way up for a while then down for a while and way up again. It was in a closed demo room that had a glass window in the door (it went down for a while well I was looking in the window and the oldest sales guy asked of it sounded better). I wasn't there for very long so I just took a quick look in the room and didn't bother going in to ask questions. They had two sets of PSB Image 6T towers setup. One pair normally (a good distance from the front and side walls in the rectangular room) and the other pair turned upside down sitting on top of the first pair. Couldn't see if there was a second sub, but there was what looked like an Image Subsonic 6 right beside one of the tower pairs. I have no idea how the sub/subs where wired in (ie using their crossovers or just from the LFE of the receiver) or how they were powering both sets of towers. My question is what would this accomplish. Could stacking the towers improve the sound or would it be a detrimant and why?