I have a feeling that this is a situation where an elegant and large great room or family room is involved. Perhaps not enough cabinet space to put in a direct fire sub neatly?

Use the Sonance Cinema ll system... Use both subs and you will never look back. There are few applications where this system won't provide more than ample discrete performance that exceeds the clients expectations. They also feel good about themselves that "they" are savvy enough to hire a company that does things as exotic and cool as in wall subs that kick the ass off many great in room subs. Now they can show it off even more to their friends. They [the in wall subs] do have a large grill hat sticks out an inch or so; nevertheless, placement can be done easily and discretely.