Control volume of headphone connected to monitor

[pkyoung]

I installed BetterDisplay to use with my new Dell U4323QE monitor. I listen to audio through headphones connected to the monitor’s headphone jack, and I want to control the headphone volume using DDC Control. However, when I adjust the volume in BetterDisplay, it changes the monitor speaker volume instead of the headphone volume. The headphone volume remains fixed at the maximum and does not change. How can I use BetterDisplay’s DDC Control to adjust the headphone volume?

[waydabber]

This is a display specific issue - most displays that support DDC volume control will allow controlling the headphone out volume, some don't. There might be some display specific DDC commands to control them separately, but I never actually encountered an implementation like that (you can use betterdisplay get -ddcCapabilities to query the display about supported DDC commands if betterdisplaycli is installed: https://github.com/waydabber/betterdisplaycli). If you use an external speaker connected to your display, it might be better to simply connect it to your Mac - if it must be connected to the speaker, you can use software audio filter driver based apps that alter the audio stream itself to control the volume (eqMac, etc).