The C64's SID sound chip was ages ahead of anything else on the market when it was released, and it was nearly a decade before the IBM PC produced anything comparable with decent software support. As far as I know, the C64 was the first platform ever to produce dedicated game-music composers.
Here's a sample of what it could do, by the legendary Martin Galway: https://www.youtube.com/watch?v=nf29ShkoAiA
And here's a netradio station that exclusively plays remixes of C64 game music (!): https://www.slayradio.org/ (listening links on the left)