OK, here's something I've never seen before since the introduction of the Mac way way back in like 1985.
I can take any program and play it through the onboard MacBook Pro speakers. Makes sense, right?
And when I plug headphones into the headphone jack on that MacBook Pro, those same programs play through the headphones instead of the speakers. Still making sense, right?
No matter what I do in Geist2, I can't get it to play through the headphones. Even if headphones are plugged into the headphone jack, and even if I open up the Mac System Prefs and choose Sound>Output>Headphones (which will be the default if they are plugged in), Geist2 will continue to play through the MacBook Pro speakers.
Maybe this is a bug when said MacBook Pro is running Mac OS Mojave?