My computer runs Windows 10 Enterprise and its NVIDIA GTX 1080 connected to one monitor via DisplayPort and two additional displays (HDTVs) that are normally turned off, via HDMI. Monitors are set up the following way:
- My desktop 4K DisplayPort monitor is set as display 1
- Both the 1080p HDMI displays are mirroring each other as display 1, so that whenever any of them is turned on, it becomes display 1 (it rarely occours that they are both on)
Both the HDMI HDTVs and my main DP monitor have built-in HDMI audio, however the audio on the monitor is unused (I instead use speakers connected via 3.5mm jack).
If I start my computer, even if I press Win+P to use "Second Screen Only", I only have my 3.5mm jack speakers listed as audio output when clicking on the sound icon in the taskbar.
Even if I open Sound settings inside the UWP ("modern") Settings app, I still don't see the NVIDIA High Definition Audio devices. This is quite strange as I've been perfectly able to use my setup like this in the past on both this and another computer.
To get the digital sound outputs from the video card to show and to activate, I have to click on "Open Sound Control Panel" or manually open "Manage audio devices" in the Control Panel. Interestingly, one of my monitors (called "DENON-AVAMP") is duplicated as a sound device, as can be seen here:
I don't know what event triggered this issue, but a full Windows reinstall is out of the question: my current install is about three months old, and so is the system.