Need to buy a decent subwoofer, and I'm totally up in the air in respect to the choices out there. I have a small HT room (roughly 10 wide by 16 long) im using a Denon receiver with bose front stage and yamaha rear. Usually you will see the built in amplifier subwoofers, but does anyone recommend getting a pre-amp / amp set up for a sub? Something with a little more control over crossover point? Id like to get a nice rich sounding subwoofer that can handle the explosions, this is for theater use only... never use it for stereo really. I'd like to stay under the $500.00 mark if I can.