@mapman
fwiw, I was listening to the same recording (Klaus Tennstedt conducting the London Philharmonic in Mahler Resurrection Symphony from the LPO house label) played both on AirPlay and Chromecast yesterday. Streamer is Cambridge Audio CXN 60, source was Apple Music. For some reason my Android phone wasn’t able to cast to the streamer, but my Android tablet was able to. I had to charge tablet up so while that was occurring I used an iPad, which apparently won’t do Chromecast afaik, so I used AirPlay to the CA while awaiting the charge on the Android tablet.
Chromecast easily beats AirPlay. The work starts arrestingly with violin tremolos followed by slashing double basses, which were much fuller with Chromecast and threadbare on AirPlay. The mid range was much fuller on Chromecast.. And while I don’t have a CD for this particular recording, in the past I’ve done comparisons with CD vs AirPlay and found AirPlay to be wanting in comparison, albeit a step up from Bluetooth .