Open Radar

 
When I attach an audio device to my Mac, e.g. an HDMI display with built-in speakers, macOS reports its volume to certain apps as 0 (e.g. Microsoft Teams tells me that my volume may be too low to hear) and disables the volume control buttons, forcing me to go through the display's atrocious on-screen display menu.

The volume controls in iTunes, on the other hand (just like the volume controls in Windows 10, if I attach the same display to a Windows PC), on the other hand, leaves the volume controls enabled and lets me use the standard media keys on the keyboard to change system volume nonetheless.

So macOS obviously has the ability to reduce the volume when playing through that screen's speakers (even if only in software and not by adjusting that screen's own volume setting). Please enable this functionality for all sound output devices. I believe the confusion of having two places to control volume, the display and the Mac, is outweighed by the ability to e.g. plug a headset into the back of a display that just passes through audio without blowing my ears out, and the convenience of having the Mac control volume no matter where its output goes.