flysurfer – I added the -D commandline option but iot does not make any difference. Although I can see the similarity to DoP this is not DSD encoded flac but rather DTS. That may be important. Do you have any other thoughts on this? It must be possible as passthrough is pretty routine – e.g. Kodi in max2play can do it! And as I said before pic***pl**er could do this until they broke it without explanation.
Thanks again for all your help.