> (events (ex1 20 57 70) "/tmp/test.midi") > > generates the midifile but doesn't play it. > > What am I missing? > nothing. it should work and it does on my system. first thing is to see if the hook is actually getting called. try the following (set-midi-output-hook! (lambda (x . args) (display x)) then generate a file and see if you see the filename printed if you do then the hook is working.