Another note I forgot to mention:

If you play a game with Redbook audio on the Playstation with a disc swap method, the music probably won't work at all. If the game you boot with also has Redbook audio, you might get some music, but I still don't think it works correctly (unless you get lucky).

I noticed that with Donpachi.

I'm not sure about the Saturn. There have been times when FO or I had trouble using the ST-key, so we had to switch systems.