Quote Originally Posted by kexodusc
Maybe you have high expectations?
I think that is exactly what is going on here. You have to remember that a subwoofer is a powerful beast. That is why they exploded in popularity. Note that before the explosion of home theater, subs were a rarity. Towers with six 6" woofers were even rarer. "Floor speakers" as towers were called in the 70s and 80s almost always included 12 and 15 inch woofers. Manufacturers did that to produce the gut wrenching bass your looking for.

I have a similar set up. Yammie 1500 feeding Yammie 170watt Separate Amp, Paradigm towers with eight 6.5" woofers, and a Velodyne 8" sub. While my towers are satisfactory without the sub, turning on that single 8" woofer starts shaking the walls. In your case, I would be surprised if at lower volumes your sub is giving you an exagerated bass response. A Radio Shack spl meter and test tone CD would reveal such a problem.