Having had bad luck with integrating subs in the past, I had pretty much given up on using one for music. When I saw the Polk PSW-10 for $180 at CC, though, I said "what the hey" and decided to give it a try (I could always return it.) It did not integrate well with my Mirages, but when I tried it with my Polk Monitor 50s, it blended perfectly. Now I am very pleased with the overall sound (and it looks great too, having the same visual style.)
One reason I tried it is that Polk subs are not known for being very powerful (at 35 Hz and 50 watts, the PSW-10 is no exception.) Living in an apartment, this is a good thing. I do think that it enriches the sound without upsetting the neighbors.