Physics of downward firing woofers

Jim - thanks for bringing it up

ivan and Erik - thanks for food for thought 

Bass waves are many feet long so the floor a few inches away doesn't have any bounce effect really.  The sound typically radiates out Omni-directionally and this decreases bass resonance in the room.  ATC makes down-firing subs and it's not cosmetic at all.  Even the pro versions that don't take cosmetics into account fire down.  I've had both down and front-firing subs and I think down-firing is a fine decision.  You probably can't get the perfect integration that you could theoretically get by having the sub lined up with the speakers so the whole system is time aligned and all frequencies arrive at the same time but the problems with deep bass in most rooms mean you don't typically have the sub lined up that way anyway.  It's usually placed to be out of sight or placed to minimize bass peaks and valleys caused by the room's resonant frequencies.

Another thing, some speakers have down-firing ports which is the same idea.  A long time back I went from B&W 804s to 802s.  The 804s had front ports and the 802s had bottom ports.  The measured in-room response of the 802s was dramatically better in the deep bass.  It was very close to spec whereas the 804s had huge variances. 

I noticed Revel started doing down-firing ports on the ultima 2 line.  It has its advantages.

Works great with a subwoofer but is totally wrong for proper bass woofer 

How about upward - firing woofer ?