without being a picky person.. what kind of sub would be needed to fill a 15x15 room? what kind of sub would be needed to fill a 25x25 room? how bout 25x40? im interesting in finding out what kind of sub (driver size) would be needed to fit rooms of certain size. is it humanly possible for a 8" sub to do better then a 12" sub without sabotaging the 12"? how big of a room can a PB2+ fill? Is any room to big for a B4+?