Depending on your financial position Energy (made by Mirage) makes an awesome little ground pounder. They come in 8" 10" 12" 15" and 18" sizes. Take a listen if you can you will be amazed at the quality of sound for the resonable price. The 8" sells for about $299 the 12" is $599. You may find an 8" or a pair of 8" is all you need. The new Dolby Lab's recommendation for subwoofer placement in a 5.1 room is to use 2 woofers and place one on the X axis of the room and the other on the Y axis of the room. I have a 19 by 19 theater room and 2 of these 8" woofers and my floor shakes like crazy!