Amazing port! Question, have you ever thought about utilizing $f4 $02 in your ports? It helps smoothen ports out by reducing the silence in between notes. Not for every port for example like the Underground theme for Yoshi's Island or Big Boss but on some songs it helps match them to their original counterpart but especially in ports of songs outside of SNES games. If you do use it, make sure to always place before anything that plays and if the song loops on itself, place an intro commands right after it, else it'll toggle upon loop.