Thanks. Yes, indeed it exists and when connected directly to the display it works OK.
But of course the display does not support HD Audio (and display built-in speakers suck). When adding a pre-amp in the mix like this:
PC -> A/V pre-amp (DolbyTrueHD/Atmos/DTS MA/DTS:X/Auro decode + HDCP 2.2 capable) -> 4K display
It does not work with HD sounds.
Firstly it is difficult to get HDCP 2.2 to work. Have to switch on the devices in specific order or I do not get HDCP 2.2. When I do get HDCP 2.2 UHD blu-ray (and Netflix 4K) will play fine. Running the Cyberlink tool also confirms all is fine:
But then I cannot get HD Sound...
If I switch on devices in "wrong" order so that I do not get HDCP 2.2 then HD Sounds work fine in e g normal blu-ray so they are supported.
It might be that it is not possible to combine HDCP 2.2 and HD sound with my setup
My motherboard has LSPCON chip to convert DisplayPort to HDMI 2.0 (all Z170/Z270 boards with HDMI 2.0 have this). And I have read mixed info that this might be the problem. But the strange thing is that it does work wthout HDCP 2.2 and the LSPCON is used also in that situation...