Chromecast Audio is dead and discontinued. Sonos is too expensive. The WiiM Mini is the true affordable streamer that does multiroom audio and more.
WiiM's Mini Streamer is a Google Chromecast Audio Sound Improver
WiiM AMP review: flying high on value for money
The WiiM Amp is a stream-everything receiver with Mac Mini vibes - The Verge
WiiM's Mini Streamer is a Google Chromecast Audio Sound Improver
WiiM Pro Airplay 2 Receiver Chromecast Hi-Res Audio WiFi Multiroom Streamer, Works with Alexa, Siri, Google
WiiM Pro Review: Best Music Streamer for Most People - CNET
Finally, a HiFi alternative to Chromecast Audio: WiiM - RouteNote Blog
Reviews for WiiM Mini
WiiM's Mini and Pro are the Chromecast Audio's real replacement - The Verge
WiiM Pro Streamer Offers Great Value For Bringing Old Hi-Fi Up To Date