recomended musical sub for 2 channel audio


I am looking for advice on a sub to add depth to my 2 channel audio system. thinking of rel but have never had a chane to listen too.
room is 13 x 26 set along long wall at one end ( not ideal)
system details
proac 1.5 speakers
mit 750 bi wire speaker cable
marsh msd a400s amp
audio research ls 16 pre
cal audio cl 15 cd
mit 330 shogun low impeedance balanced interconect
mit 330shogun rca
I listen to a little everything but love piano, vocals and jazz
narunner1
ACI Titan for sure. IMO, it is the most musical of all subs I've heard: Rel, Martin Logan, Klipsch, B&W, Sunfire Jr., Polk. It is also the best looking and most versatile: continuously variable phase and cross-over. And if you don't like it you can send it back for a refund within 30 days. You owe it to yourself to check it out:

www.audioc.com

And check out this review:

http://www.enjoythemusic.com/magazine/equipment/0405/acititan.htm

Do it. Get a Titan. I swear you'll love it.
The most musical sub for a reasonable price that I've heard is the one I own - the Nola Thunderbolt. The RELs are very good as well, but I'm happier for less $$ with my TB.

The TB is fast, articulate and musical. Absolutely rave reviews from everyone who's tried one (or two). New one (mkIII) are $1695 new but you can find the mkIIs on A'gon under $1000. A steal at that price.

Check out the reviews at www.nolaspeakers.com
thanks for everyones advice. I'm going to look at a used storm 3 on saterday for 1095
Narunner1,
You said:
"I'm going to look at a used storm 3..."
What did you think?
-Bill