Just bear in mind that not all 12 inch subs are created equal. I also recommend SVS, they are built like tanks. I use a SB-2000 (12" woofer) in a room similar to the OP's and have to keep the sub's volume around half way to stop my woman's ornaments from rattling off shelves. I also use a SB-1000 nearfield under my computer desk where it doubles as a footstool and it serves both purposes quite nicely.
