Anyone use these: http://polkaudio.tranguard.com/details.asp?item_id=2757 ? If so do they really work? What are the differences you see (hear) if any. Also what are your opinions on stacking equipment on top of each other due to space constraints. I would never stack anything on top of my receiver (heat), but I do have my DVD player on top of my CD player because that is the only place for it to go.