Background Music, a macOS audio utility: automatically pause your music, set individual apps' volumes and record system audio.

A small tool for changing sound volume even for aggregate devices cause native sound volume controller can't change volume of aggregate devices (it was always pain in the ass with my laptop).

Features:

Changing sound volume of every device (even virtual aggregate device volume by changing volume of every device in aggregate device)
Changing default output device
Native appearance (looks like native volume controller)
Media keys support

I think it can be very useful if you're using VoodooHDA with 4.0+ sound on the board (my use case), but you can find another use cases.