Start with a Sony - SA-WX700, it has 250W digital Amp, with Dual 10" Drivers, isobaric. This question is for subwoofers in general though. You have a volume knob on the Sub, and a individual volume adjustment for the sub preout from the reciever. What we have noticed is that if you Turn the Volumne on the sub 95% of max and turnt he Sub Volume preout on the reciever (yamaha HT5440) down to -12 (on a -20 to 0 scale, 0 being max). Doing this seemed to generate a crisper thump at the same volume level than having it set up (standard) with the Sub volume at 50% and the Reciever sub volume setting at 50%. This standard setup would create more a a slurred typ thump compared to the before mentioned setup. Is this hurting anything on the sub, as we don't hear anything outn of the ordinary (popping, or humming)? The bass response just seems to have gotten tighter.