Suuuper fun! As a fellow music lover / game maker this obviously wins a top ratings from me. I thought colouring the different tracks was a great way to implement the requests (and I liked the extra effort of giving them different sprites even though you'd colour coded them).
It reminded me of that app/website incredibox except with actual gameplay put on top!
My only critique would be that disconnecting and reconnect different modules felt a bit finicky at times and didn't work intuitively, although I'm afraid I cant quite put my finger on what would've been intuitive.
Nevertheless great entry and nice take on the theme
ps: glad to see another musical take ; )