Here Mr. Mouse demonstrates what will happen if you boldly stick the FM-YAM in the Expansion port of the SFX Sound Expander that is normally reserved for a MIDI cartridge.
Tune 1: 9:02
Tune 2: 9:48
Tune 3: 11:08
Tune 4: 12:23
Tune 5: 13:26
FM-YAM by XeNTaX
http://c64.xentax.com/index.php/fm-yam
Vibrants FM, the music demo for FM-YAM/Sound Expander
https://csdb.dk/release/?id=157163
Edlib, DOS tracker to make music for FM-YAM
http://chordian.net/miscellaneous-files/