The shield is the only mainstream device which supports truehd on plex.
Also, there are 2 kinds of atmos, truehd + atmos from Blu-ray, and streaming (dd+) atmos from streaming providers (ie Netflix etc).
There are no known sources of dd+ atmos other than rips from streaming.
There is no consumer available method to convert truehd atmos to dd atmos.
See also [INFO] Plex, 4k, transcoding, and you - aka the rules of 4k
