I recently discovered, after a while of wondering why the audio quality in windows was worse than fedora that the automatic windows audio enhancements actually made the audio significantly worse 😅 meanwhile I still haven't figured out how to stop windows from randomly switching the audio source from my headphones to my nonexistent display monitor audio.
it would be "simple", if start->settings wouldn't point me in an completely wrong direction. As it is, you need to know the secret phrase "device manager" (or "control panel" or "management console") to find the hidden settings-dialogs that will actually solve the problem.
Right-click on the Sound icon, then Sound Settings.
You get to: System > Sound
You can do stuff directly in the first panel, but scroll down:
System > Sound > All Sound Devices
Find your Display there, it could look like:
Click on it.
The first option in the detail view is to toggle it as a sound "output" device:
The options are "Allow" or "Don't allow". Once it's blocked, it's no longer in the list of options for switching easily between sound output devices (automatically or manually).
You should be able to disable your monitor's non-existant audio device in one of the settings menus. On Windows 10 it's in the old style control panel's audio device settings.