Thanks a lot for clarification
so I'll wait and use the windows 10 installation for now.
there - everything is working nicely - had my first 4K movie with DTS HD playing.
One last thins came to my attention (maybe due using the lastest nightly 64bit master build?)
when using the kodi wasapi as audio output device sound output is silent every some (maybe 5 to 10?) minutes for a couple of seconds (no sync issues - just no sound).
switching to directsound hdmi device "fixes" the issue but its not the preferred output device as described here for example: Windows_audio (wiki)
anyone had issues so far with kodi 64bit - Wasapi - win10 - hd audio ?
thanks a lot!