Descent was one of the first games I played on my Intel 1 PC, thanks to two floppy discs containing a demo version (supplied by the gamemagazine PCFormat). Back when it launched it was a sensation, with fast gameplay in a complete 3d environment, and I believe it still holds up today gameplay wise.
The demo contained the first seven levels of the game, which also contains some of the more interesting level music. I played the game using OPL3 Midi, and that's also the version I added here. If you want to get the full soundtrack (and also check out the SC-55 version), you can find it on the DXX-Rebirth website.
The soundtrack has a overall dark, athmospheric feel to it, ideal for flying through claustrophic mineshafts..most tracks are pretty down-tempo, with lots of bass melodies and subtle effects.
There are roughy 30 tracks including credits and title etc, but overall I can recommend the first half of the OST the most; the first tracks contain the most variety and interesting melodies, while later tracks seem more quiet and flat.