Some time ago, I posted that I had been experimenting with subs in a "Near and Far" configuration.
This can be set up in many ways, and while I have 4 LARGER subs, I recently used just a pair of them.
1) Position = Near
This one is a Larger sitting inches from the back of my listening chair, and firing away from me.
2) Position = Far
This one is about 20-25' away and down a hallway leading to my daughters bedroom.
I run these subs off an NHT X-2 crossover, which is used as a "lowpass filter", and my RM40's are run "full range".
Crossover is also set to "MONO" to the subs, and the frequency dial is turned down to 30Hz (lowest setting) so they are only hitting the "lower registers".
If your home is set up in any way to try this type of arrangement, I think you might find the results are pretty spectacular in the "Musical Foundation".
It is hard to describe. It is as if your walls disappear and the air in the room all shakes and moves. Lows seem deeper and transparent, as well as somehow making the room sound "cavernous".
On Orchestral pieces, it really sounds like Carnegie Hall, or what I assume the Met might sound like. (I need to make it to Disney Hall too, since it is right here)
Oh and for HT. . . .forgetaboutdit aa The AIR in the room and the ROOM itself seem to shake.
Played the Faux Earthquake scene out of OCEAN's 13 the other night and my heavy (and I mean heavy like in 2" thick) wooden doors were shaking

Even though I have a separate 2channel system, to my HT system, I have the subs hooked up to both systems (NHT-2 makes this possible)
So if you have the room and a couple subs, I seriously suggest giving this config a "roll" and after a little moving things around (as in slight adjustments to the FAR sub's position)
If you already have 2 subs, you're already there.
If you only have one, I can help you aa aa (in a LARGE way)