I'm guessing the Apple TV internally transcodes the DD+ to fully-fledged Atmos, so what the AVR sees is "lossless," even though the source is lossy.Ah, goodness. Makes sense. I don't even see playback options. Just plays in Atmos, for me. Oddly, my AVR doesn't say DD+ like I believe it did for Tidal.
Some kind of trickery at play here. Or I'm confused. Or both!