Assuming your ATV, iPhone and iPad are all pulling from the same source music catalog, then it is just different ways to deliver a lossless 44/16*** or 48/24 digital stream to either your Cambridge DAC or the DAC inside your Marantz for processing. On your ATV, make sure the Music app is set to lossless audio output. ***one caveat, your Cambridge is an Airplay2 streamer and Airplay2, as opposed to Airplay1, downsamples everything to lossy AAC256 it appears. IMHO, a minor difference in sound if any, but something to be aware of: https://darko.audio/2023/10/apple-airplay-isnt-always-lossless-sometimes-its-lossy/