German audio firm Raumfeld is known for making some nice (and expensive) speakers with support for streaming services like Spotify and Tidal. Starting today, those speakers also support Chromecast. The update is rolling out to all of Raumfeld's WiFi speakers this very day.
The gist is that after the update, Raumfeld WiFi speakers will appear as cast targets in any audio app using the Chromecast API. Most of the speakers with built-in Chromecast support are on the expensive side, and Raumfeld's are no exception. The smallest single speaker is $199, and the next step up is $499. Raumfeld's large tower stereo speakers will run you a whopping $1,899. There are a few other variants sprinkled in there as well. You can see all of them on Raumfeld's product page.
If you decide to pick up a high-end speaker with Chromecast support (Raumfeld calls it Google Cast in the PR, but that's not the name anymore), all the Raumfeld speakers are available on Amazon with Prime shipping. Despite the high price, they do seem to review very well.