high end subwoofer...which one tho?

Like a good que butt can be used with both a snooker and straight pool shafts a good sub can be used for both two and multi channel systems. Today it's setup and EQ that intergrates any sub into the room. IMO JL and Velodyne will make this a simple task especially if you don't have room correction, and also provide the ability for truly deep output. This same EQ will allow any size sub to be used even in a small room, not that you need it though. I use a Meuci Power Piston and two Velodyne DD10's.

I like the Revel B15. I run two B15s and they are front firing. In a small room one would be fine. I had a HSU Research big guy, but it was down firing and caused my wood floor to rattle. I do not have that problem with the front firing B15s and the position in the room was the same for both subs.

That's a small room for now and you would not 'need' the formentioned however it would be useful and work later for a larger room. I would opt for a svs 13...just because of the fact why pay more. Take a look at Elemental Designs (ED) subs as well. Killer performance, killer price, and free shpng for something that weights as much as all your gear put together.

The SuperNova MKIV-12 is terribly insane in performance, with more than 100 decibels of power...it will shake the walls.

I have 2 definitive technology supercube reference subs in a 14 x 22 foot room. These have one 14 inch sub with two 14 in radiators. Internal amp 1800 watts. They are awesome for two channel and HT. cost $1900 each.