Ah wonderful. Putting Apple MIDI Driver and MIDI Manager in the root folder did the trick. Hoyle Classic started up right away and sent sound to my MT-32pi. Too bad it is pretty slow on a LCIII. I also tried Thexder (v1.0.1 from Macintosh Repository) and it started but then died with an error. Maybe it doesn't like system 7.5.3? Regardless, seems like it is working now, thanks for the help!