This is sweet. Maybe you could've toned the echo volume down a little bit, but in-game it sounds very nice and atmospheric.
The only things that make me a bit unsure are:
- The way you organized the song in your channels. #0 never plays anymore after the first loop, so I'd advice swapping #0 with any of the SFX channels (I highly suggest #7). In-game, the cutoffs aren't too noticeable, so it's ok.
- What you do in #7 is questionable, as in, defining a sample more times when it's not needed. Example: