what are some things in rooms that could cause problems.. I.E, lack of carpet? concrete walls? My basement is mostly carpetless, with a concrete floor, and a big rug in the middle (roughly) Also my walls are concrete, with drywall about 1" off the concrete.... the rest of the walls are internal and hollow. i want to buy a carpet and may do that in the near future. whats that foam stuff that looks kind of like egg carton and does that do any good if you cover your walls with it? even just a slight difference? EDIT---- (this is about speaker placement mainly) Also should a subwoofer be in a corner facing INTI the corner or facing AWAY from the corner. and where should a sub be located in relation to the mains? Does it sound bad if you have the sub beside one of the L/R speakers?