Hi Gecko,
You don't really want to be using an ATV for this.

As far as I know, the ATV only outputs at 48k - hence is transcoding all the 44.1k material from TIDAL received over Airplay.

I currently use my Mac via Airplay to an Airport Express - this maintains a 44.1k "bit perfect" stream to the optical and into my G91.

Matt

#1 - MC200 1TB, G91DH DAB, DSP5200, DSP5200HC
#2 - Explorer2, UE900