Could there be a quest rule to fade music when going through a warp with an animation? Insta-Warps wouldn't be affected by this, but transitions like caves, scrolling warps (maybe an option to enable it per warp), and Open Screen would fade the music as the animation played. I think a one-second fade time would work pretty well
Fading Music
That'd be fancy. I wouldn't use it, but I'm sure that some really epic feeling quests could make good use of this. I'd suggest it as a screen data option rather than a quest rule. It'd be more flexible that way.