The current commit, 5cf5f1e, is in use on my SD2SNES, running on an NTSC Snes Mini. Currently, the .pcm audio seems to have trouble loading at seemingly random intervals. Whenever this happens, usually there is silence, but at least once, a loud 'buzzing' was the result. The issue resolves itself whenever a new audio track is loaded, but it is problematic.
If I had a guess, the current code that selects and plays the desired audio track doesn't seem 'fast' enough to always successfully play. If nothing else, may I suggest a fallback where after each load, the MSU-1 can check to see if audio is playing properly, and if not, it will play the .spc audio instead?