... what's your budget?
You need an amp. Or several amps. One for each "zone".
In the Amazon world it'd be an Amazon Echo Link Amp ($300). Or you can go rich and go Sonos Connect:AMP ($500). Alternatively, you can get the Amazon Echo Link ($200)/ Sonos:Connect ($350) and connect it to a cheapo amp / amp you already have.
Chromecast audio + amp was the cheapest way to do this, but it didn't catch on for whatever reason.