Which Android devices support Amazon Music HD? Most Android devices released since 2014 can support HD/Ultra HD playback (up to 48kHz). Please ensure that your device is running on Android Lollipop, or later.
At this time Amazon Music HD is not supported on Chromecast.
Also the app (when you touch the badge) does not report the bit rate etc when casting. It just puts up a message to say it can't.
My Cambridge CXN v2 plays Tidal in hi res via the Cambridge app and the sound compared to Spotify is marginally better, however when I cast via Google Chromecast from Amazon hd app the sound quality is no different to Spotify. Therefore I may either stick with Tidal or more likely re activate my Spotify subscription as the minor sound difference does not really justify the additional cost