I'm confused. I have seen nothing on the Chromecast Audio that says anything about different services being limited to only working with the analog outputs, and Spotify was one of the services they demoed it with. Tidal's app doesn't support Chromecast yet, but it's supposedly going to be out shortly.
https://www.google.com/intl/en_us/ch...ers/#?discover
Oh, I see, Spotify didn't support Chromecast until these new devices: http://venturebeat.com/2015/09/29/sp...omecast-audio/