i now know 16 ways to run fluidsynth on a raspberry pi that _don't_ work. Fortunately, I know _one_ way that does.
In the end, I needed to specify alsa instead of Jack or Pulseaudio.
yes, it may be completely obvious to some of you. It wasn't to me. I don't do much with the various sound backends on linux. The error messages (if any were presented) weren't obvious to me. This is not to shame the project (which is awesome) but to illustrate: you can work with this stuff for 20+ years and still take three hours to get a seemingly basic thing working.
