What's a "Moral Compass Cricket Thingy"?

[Maniakkid25]

Realistically, you can't. You would want the "stems", or individual instruments of the song (most songs are built piecemeal, rather than played all at once in a single recording). Once a song is released into the wild, it's just one giant mash of frequencies that you'd need to pick apart individually. I guess with some software trickery, you could isolate frequncies, but not to the point that you'd retain the original timbre of the instrument.

Edit: and immediately, now that I think about it, that "software trickery" is literally what MP3 does, but in reverse? Like, MP3's whole schtick is that it takes out the frequencies that do not add anything to the song, and that compresses the file data. Theoretically, a human with the code of an MP3 compression algorithm could reverse-engineer a way to get out individual instruments? It's a long shot, but it is a possibility, now that I think about it.