I recently bought a Yamaha HT in a box and am considering upgrading my sub. I have $300 to spend and want to get a real room shaker. What do you guys recomend? Also what specs should I look for in a sub that will really make you feel the LFE? I am currently looking at a Yamaha 270 watt powerd subwoofer with a 10" driver and these specs: Continuously variable high-pass filter (40-140Hz, -24dB/octave slope) Phase-reverse switch and volume control let you achieve optimal results with your system and acoustics Bass Action Selector System (BASS) optimizes output for music or movies at the touch of a switch Line- and speaker-level inputs, for use with or without a dedicated subwoofer preamp output Magnetically shielded to prevent picture distortion when used in home theater applications Signal-sensing circuit turns the sub on when signal is present, off when signal is absent Frequency response: 20-160Hz (-10dB) Is this any good?