There is actually a method to the madness of multiple subs.
Seriously. There is something out there that is referred to as a distributed bass array. It is ideally four subwoofers placed in exact spots within a listening room, placed largely by ear (although someone could probably use an SPL meter or professional RTA device with a mic to do it).
The first sub is placed at the listening position. From there, using the proper test tones, you go around the perimeter of the room to find the spot that has the most balanced bass response. Place the second sub there. Go around the perimeter again, find the most balanced spot, and place the third there. Do this also for the fourth sub. Finally, listen around the perimeter again, and this time move your first sub (at the listening position) to that spot, but reverse the phase. This setup has the effect of minimizing room modes and fully energizing the room with bass. The volume does not need to be up very high either. I saw one system out there that included four subs and a 1,000 watt Dayton class D amp, but I would think it should work with any type of sub. (Four wireless subs would be ideal IMHO, although balancing the volume could be tedious.)
Or if not, yeah, sure...four solid walls of 18" woofers gotcha covered, mang.
