I'm a huge fan of Klipsch and their new powered subs — so much so that I have two 12" subs in my own home theater system and absolutely love them. The depth and power of bass that they deliver is incredible. If you want to add the same performance to your system, consider the Klipsch SPL-120 or better yet two for a more even sound.
This hard-hitting 12" sub is powered by a 300-watt RMS amplifier — enough "oomph" to shake the walls but also provide controlled, accurate bass. It's the kind of sub that makes you feel the dinosaurs from Jurassic Park stomping into your room with a new level of realism.
Line-level and LFE (Low-Frequency Effects) inputs let you easily connect the SPL-120 to almost any home theater or stereo receiver. Its back-panel gain, crossover, and phase controls help you fine-tune the bass to your liking, and blend its sound into your system.
One day I decided that I'd had enough. I bought an isolation platform to decouple my sub from the hardwood floor. Voila! Just like magic, the rattling and vibrations instantly disappeared. I even had to dial the sub back because the bass was suddenly stronger. It is without a doubt the best money I've ever spent on my system.
Klipsch SPL-120 owner's manual