I appreciate that the center speaker neest o go directly below the screen but how far below the sceen is acceptable? My TV (Panasonic DT30) doesn't have a particularly tall stand so I can't lay it on the same shelf as the TV is on else the picture would be blocked. The 3 shelves below (will) have other things on them (PVR, PS3, Mac Mini, AV Amp) so I'm wondering about laying it on the floor (carpeted) but not sure if that'll be too low. There isn't much I can do about it if it is too low - it'll impact my purchase decision.Thanks