high end subwoofer...which one tho?

One quick additional thought:

In a smallish room, you're not going to need a monster sub - and a 15" model from any of the brands that have been recommended here will likely provide crushing bass capability in your room. The 12" SVS cylinder is probably more than enough.

As Bob pointed out, the addition of DRC (like the Audyssey chip included in many HT receivers and pre-pros) will almost certainly be extremely beneficial to bass performance in your space. The difference between DRC/no DRC will likely dwarf the difference between choosing the best sub versus choosing a merely good sub.

Marty

My rythmik 12" seamlessly integrates with my paradigm signature S2 bookselves. My crossover is at 100hz. This sub will be as transparent as any other sub out there, at any price. The only thing to consider is the headroom. I believe the JL will play louder. My room is 20X20 and the sub fills the room for both HT and 2 channel. It is one of the great bargains in audio. I sent back several subs before settling on rythmik.

The Submersive by Mark Seaton is very good. There are upgrade finishes also available.

Will

you can't go wrong with any of those brands

i still say the old velodyne ULD series are some of the best subwoofers ever made. pretty cheap on the used market...if you can find one.