I don't know how you played this game, like on an emulator or whatever, but the reason why you could switch between PSG to CD soundtracks was yet another quality of life feature. Using PSG sped up the game drastically to remove the CD loading time, and I mean it was seriously noticeable. Especially if you needed to grind, you definitely turned on PSG. This is by far the least annoying RPG to grind in I have ever played to this day.
I don't know how you played this game, like on an emulator or whatever, but the reason why you could switch between PSG to CD soundtracks was yet another quality of life feature. Using PSG sped up the game drastically to remove the CD loading time, and I mean it was seriously noticeable. Especially if you needed to grind, you definitely turned on PSG. This is by far the least annoying RPG to grind in I have ever played to this day.