I am in the process of shopping for my first HT sound system, and am looking for advice on subwoofers. Namely, what is the difference in performance between front firing and downward firing units? I haven't found much discussion about this, but it appears that newer units are mostly forward firing. What might be better for my situation? I am not concerned with music, only HT. The room is 22ft X 22ft, 9ft ceiling One wall is virtually all glass: windows that look out over my back yard Slate floor (no carpet) Because of the slate floor, I think the subwoofer has to be placed at the front wall, next to the entertainment center, as there is no way to run wires throughout the room. The rear speakers are built into the ceiling near the back wall, pointing down at an angle.