You make a good point, Ragna, that I had never considered before. If it's easier to do a music mod on the PSP, I'm totally willing to give that a try.
However, I'd still rather use the PS1 if at all possible, because there's a huge, glaring issue with the PSP version: all the gameplay changes. This includes new items (e.g. Phoenix Downs), accelerated leveling, different magic system, and auto-targeting (not a bug-fix!), all of which make it a very different, easier, slightly crappier game.
(Not to mention some non-critical stuff that I don't personally like, e.g. running through towns and the added dungeons.)
The other reason is that if I was hoping to do any graphical changes, I felt it would be easier to do it with the lower-res sprites in the PS1. That's if it can even be done in the first place, though, so it's also not critical.
Actually I've been thinking of commissioning a non-pixel-art artist to draw the sprites more in Amano's original style, and maybe this is easier on the higher-res PSP after all??? So geez I don't know.
Anyway I figured the PS1 could be tricked into reading the music like on-disc CD audio (called "red light" or "yellow light"? I can't remember), so that's why I thought it would be possible at all. How do they do this kind of thing with the FF7 mods?
Edit: Didn't want to double-post. Here's a playlist of everything I have thus far. All info in notes is current:
https://soundcloud.com/combe-sound/sets/final-fantasy-1-re-orchestrated-phase-ii