If you look at what
Apple actually says, what they're providing is "spatial audio" derived from Dolby Atmos sources; there's no claim that the headphones themselves have more than two channels of output and certainly not that they are sending more than two channels of audio over Bluetooth. They presumably achieve this effect through the
Dolby Atmos consumer headphone implementation, in the same way that the older
Dolby Headphone approximates a 5.1 experience with just two speakers (I make no assertions here about the fidelity of such approximations
). Apple's headphones also apparently use head positioning detection to aid in the illusion for certain headphones.
So I strongly suspect when you listen to Dolby Atmos tracks in the Air over bluetooth through your iPhone, you're getting the Dolby Atmos headphone mix through two audio channels. If you listen to it from Tidal via the car's electronics directly, there's enough information in the stream itself to get "true" multichannel, though it would be nice to confirm they're actually doing that.
