@Richard.Dane With the recent rumours about a planned lossless Apple Music to counter Spotify HiFi, it would be interesting to learn what resolution and audio formats are supported by Apple AirPlay 2 and especially on the Naim Unity family. There used to be a specification of AirPlay on the Apple website, but with the introduction of AirPlay 2 it vanished. As far as I remember, AirPlay 1 supports 16 Bit / 44.1 kHz and 24 Bit / 44 kHz with lossless ALAC and would be good for CD quality but not real High Res.