How important is the port location of the Subwoofer? My living room interiors are such that I HAVE to place the sub next to my floorstanders, flush against the wall (actually about 6 inches gap between the wall and the sub). Do I have to look for downfiring subs or rear-firing subs would be OK? If the sub port is against the wall, what is the impact on the bass? My current Sub is a JBL HTIB bundled sub with an 8 inch driver and front-firing.