I just bought an Nvidia Shield Pro today hoping it would mean that my NAS DS918+ would have to transcode less.
My TV is a 90XE from Sony which does not support TrueHD by itself, however, I was under the impression that as long as a format is supported by my shield, it should work without transcoding?
I have tried all settings in the Audio passthrough setting on the Nvidia’s Plex Player. No difference.
Have I been misinformed or do I need to change specific settings?
If you are using the TV speakers, then Plex Media Server will transcode the audio to a supported format (since, as you mention, the TV cannot decode TrueHD audio).
If you are passing the audio through the TV to an attached soundbar/receiver/etc, then a) the TV and audio equipment must both support HDMI-eARC and b) the audio equipment must support TrueHD.
If both conditions are not met, then Plex Media Server will transcode the audio to a supported format.