Avalon Eclipse's..To Sub or not to Sub

I currenlty own a pair of Avalon Eclipse's and have been very happy with them for the past 5 years. However, when I bought a decent sub-woofer for my Home Theater set up I was impressed. Does anyone have any experience adding a sub -woofer and what kind and make to these Avalon's.
We've had good success with a REL Strata III hooked up to Threshold T-200s (simple stereo setup, not home theatre as you have) in a 15 by 18 listening room. Adds a nice bit of "thump" from many CD Jazz recordings and most DVD movies, but otherwise stays out of Avalon Eclipse's way. Easy to adjust as well.
I used to own the eclipse and I ran them for a few years with out subs and then I decided to try them(a sub), with that speaker it helped an awful lot. I didn't realize how much music I had been missing.
Thanks guys, but I guess that I should have mentioned that the sub that was bought was added to my second system.....not to the Avalon's. So, what else has anybody used for a two channel system with the Avalon's I guess is my real question.
You might try a different amplifier like Rowland Concentra with a good power cord (like from Custom Power Cord Company) with the cardas Golden Cross. That should give you more bass.