Troy, that hasn't been my experience when the sub is properly crossed-over and doesn't create noise or distortion which brings attention to itself. As Mark pointed out, it's only the upper harmonics which should be reproduced by the speakers, not the sub, which allow localizing bass sounds. An 80Hz crossover to my EP500 works with no problem. You didn't describe either the crossover frequency or the present sub. An 80Hz crossover to a quality sub should be adequate to prevent localization. A 60Hz crossover would make this even more certain, but that would be a little low for your VP150 and QS8s(and you can set only a uniform crossover frequency on your 3803).
