So, I'm trying this midi file:
https://www.midiworld.com/download/652
with Munt under windows (2 different systems) and it sounds all wrong. Strange thing is, when I replay it via mt32-pi (under mt32/munt mode) it sounds as it should.
Same roms, same settings, same everything.
The mentioned file is intended to be played on a GM-compatible device, specifically it contains embedded SysEx commands recognised by Roland Sound Canvas.
However, MT-32 is not a GM-compatible device. For it to sound half-reasonable, the GM compatibility mode must be enabled, e.g. by playing the MTGM.MID file beforehand within the same emulation context, the same way as would be done with a real device.