I clamped some $5 EMI/RFI filters from Radio Shack onto the power cord to my CD player, and all of a sudden I was hearing small, low-level details and nuances that I'd never heard before. I suppose they'd been masked by electronic hash from EMI/RFI contamination--and that my background is officially "blacker" now. Music simply sounds more natural, expressive, and relaxed, and it's easier to see how musical lines relate to each other. I think Elizabeth's TV grain comparison is right on: less grain, more (and more easily interpreted) detail.
Ironically, I also think a "black" background makes music more expressive and colorful.