Sugarbrie is correct. Subs when correctly matched to main speakers and properly set up can provide absolutely seamless integration. While the effects of my SW800's are dramatic (even startling), they are quite "invisible". They don't sound like separate speakers. As much as I loved my els's before, there were very real limitations. Amazing for acoustic music, vocals and jazz. But there was other music that really fell very short of the mark. Now I realize that I was missing things even on music that was well suited to the speakers before adding the subs. If anyone hears boominess or rumblings from subs they are either: (1) the wrong subs for the mains; (2) not properly set up (not just physical placement, but also the crossover, high/low pass slopes, and crossover points); or (3) just plain garbage. Admittedly, speaker systems with subs designed into them are much easier to deal with, but most other applications just take some work and a little understanding of what's going on.