Expose individual output channels/sinks/devices

[CpazR]

The streamlined convenience of xvolume is convenient.
However, it would be useful to have access to the different outputs (maybe inputs?) and be able to modify the volume for each of them.

Whereas currently, xvolume seems to only use the default output.

To use my particular use-case as an example. I'm attempting to make a midi device interface that lets it manage volume.
So I would like to expose the different audio outputs and map them to different midi inputs like sliders and/or mute toggles.

Basically, Midi Mixer, but cross platform and open source.

Not sure how realistic this would be. I can imagine MacOS support for something like would be the biggest hurdle.
This also assumes this fits within the goals this package falls under.

Either way, just an idea I'd be interested in seeing implemented for my own project, with other projects likely being able to make use of it as well.