I've not had music in the background for a D&D session (yet). There are a few things I would like to try / experience, for serious or for fun.
The enemies are chasing us: William Tell Overture (also known as the Lone Ranger theme)
Entering the sepulchure of the Legendary Artifact: Siegfried's Funeral March (from Wagner's Ring cycle)
Activating said artifact: Thus Sprach Zarathustra (2001)
BBEG's enforcer lieutenant arrives to fight the PCs: Duel of the Fates (Darth Maul confrontation)
BBEG himself arrives: Imperial March, from Star Wars
PC tries some spectacular physical stunt and rolls a 20: Indiana Jones theme
Final Victory: Siegfried and Brunehilda in the Forest (Wagner's Ring again)
I find that it's just not worth the effort. The amount of work involved to select the music and rotate it in a timely fashion can be staggering, especially if IRL. IME this leads to a loss of immersion, rather than the intended increase. To me, the only reasonable purpose would be to add it in post-session for a podcast.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.