Obviously, it depends on the kind of game. If I was running an espionage game, I would use Jazzy, James Bond-style music. When I run Star Wars, I pull the music from the film soundtracks. I would likewise go to the source for a Star Trek game. When I run a fantasy game, like D&D, however, I have multiple resources. I’m a big fan of Tabletop Audio. I can queue up several appropriate ambient tracks and have them repeat in the background. When a fight occurs, I have a custom playlist in iTunes with battle music from The Witcher 3 and Elder Scrolls Online. I have another custom playlist with music appropriate for taverns. Rarely do I play it loud enough to drown out talking; it’s there for background ambience and should never take center stage over the players unless music is the point of the scene.
RPG-a-Day 2018 – Week Three: What music enhances your game?