4k and dolby vision is not why i am getting nvidia. I dont even have a 4k tvAudio passthrough is fantastic in Shield....Plex,Kodi,VLC etc
Just keep in mind Dolby Vision may not be supported.
I find PQ better with Sony BDP x700 than Shield TV.......only x700 sucks at decoding TrueHd in mkvs (audio not supported).
I empathise with OP as he has the same reason for which I also own a Shield