[TmanDaCool1]

I wish I knew how the heck to change Super Nintendo Music. I'm such a n00b at this. All I want to do is replace the Rainbow Road music with a different SPC from another game. WHY IS THIS SO COMPLICATED?! 

Other people can do it, evidenced by Dirtbag's Super Baldy Kart hack... so how does HE do it?! 

[Bregalad]

There is no general purpose to edit "SNES Music". All games used their own sound engines and they are completely different from eachother. Only games from the same company will use similar (but often slightly different) sound engines.

If you're intro Super Mario Kart, then you should look at Nintendo's sound engine, I'm pretty sure they are doccumented.

Also, as one of the major sound/music hackers here, let me tell you, you are wrong in beliving changing music is so complicated. If you are knowledgable about hex and music theory simultaneously, that's probably all the required knownledge. No need to even know assembly. It really isn't, not as simple as changing fonts or palettes, but definitely simpler than other kind of hacks.

[dougeff]

I wish I knew more, but my understanding is this...

At startup, the game will load an automatic program to the SPC700 memory, and send some BRR 'samples' (which can be repitched), and send some song data (the score of the song). After it's loaded and running, the main program just occasionally sends a byte now and then to signal 'stop' or 'play song #2'.
You want to locate the 'data' (not the code) being sent to the SPC700 memory. That is what you will need to edit to change the song. I don't know of any documents on this.

You might be able to get a SPC 'dump', which would have everything music related (code and data).

Does anyone know any tools to disassemble / read / edit SPC files?

Edit: this appears to be the SPC dump...maybe you already have this, but if not...
http://snesmusic.org/v2/profile.php?set&selected=2750

[Dr. Floppy]

I'm currently involved with a SMK music hack.

What song is it you wish to import?

[elveskz]

 For some time I have been working on a mod for the game Inindo Way of Ninja for Snes.
 I would like to know if there is a possibility to insert the 3 songs that were removed in the American version of this game,
 because in the Japanese version they are present and have been removed for some reason.

[Jorpho]

There is an MSU-1 hack for Mario Kart, isn't there? You can use that to replace the music with pretty much any arbitrary audio with hardly any trouble at all.

ETA: To be clear, this is the one:
http://www.romhacking.net/hacks/3656/