Sure.
In answer to @Nige_S as well, it is a menu-bar app and I utilise the built-in shortcuts to summon the menu. So in a way I do use keyboard shortcuts to open it, although not as an open-app action in KM. However I've mapped other keyboard shortcuts in KM to activate the app by just triggering the default hotkey (F8) . So double-tapping ⌥A or double-tapping ⌘. , and even a a trackpad gesture has an action to trigger pressing F8 ( which is Function+F8 on a macbook Pro). This is because the pinned menu keeps jumping out of focus and I lose control.
The goal would be to create macros that might first bring the menu to the front, select an app's volume slider and I would use Up/Down arrows to modify.
Doing all of this is probably because of a dissatisfaction with SoundSource's built-in shortcuts, which have you jumping all around the keyboard, although I am happy they exist. There are Siri Shortcuts that will help me but I'm yet to investigate them and I'd be concerned bringing yet another 3rd party app will just slow things down.
I tried OCR to detect the top left corner of the menu, but I couldn't get a stable return as 'true' after trying all sorts of options that I don't fully understand.
Thanks for your help.