First of all, thank you for all your support and searching for a solution. As I remarked before, I have several HTPC systems in my house, two of them are Kaby Lake powered. One with a Pentium G4560 (iGP HD610), one with a Core i5 7400 (iGP HD630).
1)
http://www.shuttle.eu/products/slim/xh110v/ (G4560)
2)
http://www.asrock.com/nettop/intel/deskmini 110 Series/#Specification (i5-7400)
Boot systems are equal installed (same Windows, drivers, Media software).
Number one (Shuttle) is hooked up right now.
For testing I use both video outputs, HDMI 1.4 or HDMI 2.0a (trough DisplayPort on the back and using a active adapter). Never at the same time though, I disable one or the other, when I try things out.
For your understanding, and I can't accentuate this enough, I can play anything that I can lay my hands on with both systems. In the format that the media original has. Only HDR can't be played as is (no TV popup), because Intel doesn't support it with there drivers (yet). But besides the missing popup, things are playing just fine.
So to make things more clear. Media that I play with MediaPortal (using LAV), or play with Kodi 17.x (using internal codecs), are playing smooth and fine with all sorts of bitstream audo,
but the 4k HEVC media (with HDR), looks very dull.
The reason you started this project? But besides dull, it runs flawless and smooth, just as smooth as I get when using MPC-BE with D3D active but without sound. So no bandwith issue when using Kodi or MediaPortel and playing really heavy 4k media with a very very high bitrate even media up to 659Mbit (testfile).
All my hardware is 4k HEVC HDR HD-audio supporting, all cables are renewed (just in case).
So my feeling says, the problem lies somewhere else. You follow my feeling?