I use 2 Velodyne HGS-15s controlled by an SMS-1. They're mounted essentially in the corners, but pulled out a bit. The system is used for both music and HT. A listener is unaware of the subs, except for the realization that the mains could not be producing certain sounds, the felt more than heard vibration when a low pedal note is opened on a pipe organ, for example. HT LFE does its own thing, so an explosion can make you feel the pressure wave.
I think one sub is essential, and two are better.
db
I think one sub is essential, and two are better.
db