Chromecast Audio is dead and discontinued. Sonos is too expensive. The WiiM Mini is the true affordable streamer that does multiroom audio and more.
Reviews for WiiM Mini
WiiM's Mini and Pro are the Chromecast Audio's real replacement
WiiM AMP review: flying high on value for money
Finally, a HiFi alternative to Chromecast Audio: WiiM - RouteNote Blog
WiiM Pro review: The Chromecast Audio Ultra we never got
Audioengine B-Fi Wi-Fi® streamer with Apple AirPlay® at Crutchfield
WiiM's Mini Streamer is a Google Chromecast Audio Sound Improver
Finally, a HiFi alternative to Chromecast Audio: WiiM - RouteNote Blog
WiiM Pro And Pro Plus Wireless Audio Streamer AirPlay 2 & Chromecast
WiiM Mini/Pro are perfect alternatives to Chromecast Audio
WiiM's Mini and Pro are the Chromecast Audio's real replacement
WiiM Mini music streamer review: Audiophile quality for just $99
WiiM Pro AirPlay 2 Receiver, Chromecast Audio, WiFi