Speaker upgrade

Pete, I'm going through the same situation. This advice only goes if you're grooving with your Thiels, but missing the "room filling impact without boom." Get yourself a PAIR (two is better than one in the sub department. Power plus room nulls avoided)of subs. You'll get plenty of feedback on different subwoofer possibilities. I'm waiting on delivery of two JamesEMB1500s that I will put on two Sistrum 101 platorms; also on order. That 30 foot wall is great for your bass when you have your system on the short wall. This is probably the most cost effective way to achieve what you want and maintain the (if you love it) Thiel sound. With two subs you're going to move a lot of air. In this case, IMHO, I feel bigger is better peace, warren :-)

I recommend Wilson Alexandria X-2 or X-1 Grand Slam depending on your budget. It should get you where you want to go. Add a pair of Wilson XS subwoofers if you really want to fill out that bottom end.

You may want to listen to some vandersteen 5a or quatros depending on your buget very much the same sound as Thiels. I had the same bass issues now I have the 5a couldn't be happer. The trick is they have there own powered subs that are phase correct in the speakers. This produces tons of fast bass and also provides a natural by amping so if you run high end amps they just need to consentrate on the mids and highs. I have found subs never really work out well they just don't match the speakers 100% or the volume is not consistant. The Vandersteens also have a very advanced crossover that gets tuned to the room and your equipnment so you can alwas tweek the bass for more or less bass.