The soundtrack for the C64 game Lazy Jones [1] is a pretty good demo for the legendary SID sound chip. When I experienced it, my computer has a bleepy PC speaker, and my cousin's C64 had a much more "adult" sound.
If you want to be blown away by the sounds the SID chip can produce, I would recommend some of LMan's work. This is one impressive tune: https://youtu.be/h0qMNfpiLmE
And this is done with the hardware that Bob Yannes designed for the Commodore 64, in his early 20s.
Edit: on second listen, it sounds like it has a bit of reverb applied? I wonder if it was recorded from real hardware.
one thing im noticing in this is skipped ticks in the player... mysterious brief random pauses in the sequencer, ouch, heh.
Start with Turrican I end titles and go from there.