A couple things to try, joshua, while you are waiting for a response from Dr. Hsu:
1) Try plugging a port and running the subwoofer in maximum output (32Hz) mode on the amplifier. This will result in an overdamped response, which some people feel gives a tighter bass.
2) Give us a call and ask for a second port plug, so that you can try running the subwoofer in a "sealed" mode with both ports plugged.
Usually careful placement/setup will result in a well balanced sound for music, but it certainly would not hurt to try either of these options.
P.S. We actually started designing subwoofers first with music in mind, so quality of sound with music is very important to us!
Sincerely,
Peter Marcks
Hsu Research