I recently built the Vance Dickason Titanic MKIII sub kit from Parts Express (www.partsexpress.com/
My listening room is on the smaller side, and I'm using the big TS1-R Grandes to begin with, so one could question the need for a sub in this set-up at all. But I know what I like and I figured I'd like this system even more with a stronger low end. As usual, I was right
These subs are offered in 10", 12" and 15" versions--all massively engineered Dayton drivers--with the plate amp on the 10" rated at 250w (I believe the 15"s amp is 1000w). For the reasons detailed above, I went for the 10".
With fairly minimal set-up (with the help of the Cardas/Ayre set up disc and a lot of source material I know well), this unit integrated VERY well with the TS1s.
And I sure as Hell know what "pressurize the room" means these days!
It's an easy build (no solder, for example), but because it's DIY you're getting a LOT more quality for your money. The only complaints I've heard about these subs is that the larger cabinets (not the 10") could use more/better internal bracing, which again is a simple thing to do.
These powered sub kits get very good rap on the 'phile message boards. That's how I found mine and it's not going back for that full refund, no Sir.
Good luck and have fun.