I am constructing a HT in my basement with a concrete floor (25'x14'). At the end away from the screen, I am putting a sofa against the wall (required due to architectural considerations). There is a walk-space behind this wall - I was thinking of mounting (2) 8-12" woofers w/amp and crossover in the walkspace and firing the woofers at the back of sofa for additional bass since the priamry sub is at the opposite end of the room.
Should I go diy in-wall or make/buy a sub (box)? Any other advice?
The problem with the in wall, is that it will be much harder to get the correct volume of the box, it sounds like you want something that will be top end, so I suggest either building a box of your own, or buying a subwoofer box. Not to mention that if you have your subs built into your walls you will most likely have a major vibration problem.