Hey Shaggy,
I'd respectfully argue that a good subwoofer does also improve your music. There are many instruments that dip down into the low range that a good subwoofer will enhance. Arguably, a cheap HTIB style sub will probably do more harm than good but I suspect that en EP350, even the older models, would really enhance instruments like bass guitars, celos, kick drums, tons more as those are just the most obvious.
A good sub, calibrated properly, won't make the music sound rattly or boomy. It will make it sound much more like the real thing. I wonder if maybe you had it turned up just a little too much and it gave you a bad impression with music instead of having it calibrated to blend in with the other speakers and produce a smooth realistic bass sound.
