On topic, this is great work.
`brew cask zap <app_name>`
It isn't an acceptable answer for the average Mac user, but it at least solves the issue for a subset of users.
Also I could be wrong but isn't/wasn't the whole "fat binaries + static binaries + app binary and its associated assets live in a magic folder that the OS-X GUI displays as 'the app' + other past Mac app trickery such as resource forks etc" all meant to make both app install and UN-install painless and easy ?
I know and used a few commercial apps that were a damn pain to scrub completely off the Macs I owned but that was expensive proprietary commercial software that felt the need to take my money and also saddle me with DRM to enforce their licensing.
But for most apps I've found AppCleaner to work very well for uninstalling all related files (regardless of where they're scattered about): https://freemacsoft.net/appcleaner/
Maybe Apple could provide a builtin mechanism in MacOS (as I assume/hope it's about to be called) that watches for a .app bundle being dragged into the Trash, and offers the user a chance to remove any auxiliary files created by that app, and run its uninstallation scripts if any, when the Trash is being emptied?
Of course it will have to be seamless and resistant to developer abuse (or malice) and not make everything too Windows'y.
Too bad it is abandoned software, but it still works terrific.
I'll be interested to see how you develop this.
Nothing as simple + dedicated as Background Music tho.
Background Music could totally slip into this setup!
AH's ability to send the sound across multiple output paths is also really nice and I use that (less often) as well.
And obviously having a dmg would be better too.
(I use Keysocket it every day. However, media key handling breaks when I have apps like VLC running at the same time on OS X. As far as I know, it's a Chrome bug, because it ignores SPMediaKeyTap, defacto standard library to handle media keys on OS X.)
It's only the mixer though (with the volume boost) - no automatic pause or recording system audio (not that I ever missed these).
Felt like per app audio volume was standard in operating systems, I didn't even think about it.