It may just be that this particular sub is better suited to HT, and simply won't blend with the M60s. You might want to try a sealed design for music (I have a sealed 12" sub). One example I can think of off the top of my head is the EP400, but I am sure there are others out there that might suit your budget better.
That said, the SVS and Axiom ported subs that I have heard have substantially added to music. Sadly, I haven't heard any Hsu subwoofers yet, but those are supposed to be quite good for music as well.
BTW, you want to hear all of the music out of the sub, to a point. It sounds like the crossover in the sub may not be working--does the sound change when you adjust it? At 40 Hz, you shouldn't be hearing anywhere near all of the music.
Last edited by kcarlile; 11/26/07 09:16 PM.