The Chromecast Audio allows me to plug it into any standard stereo. Bang for the buck I can get much better speakers for the dollar when buying just normal speakers instead of "smart" speakers. I then plug the Chromecast Audio into it and get the same ability to Cast to it, and include it into groups. The ability to add it to Cast groups is one of the key reasons I like it over just a Bluetooth connection.
So to sum up:
* Bang for the buck get better audio quality
* Still get all of the same Cast features (WiFi casting, group casting, etc.)
I just got the Google Home Max. It sounds better than the Google Home, but not as good as I'd expected. I'm tempted to send it back and replace it with a Home Mini and a regular set of home stereo speakers.
The ordinary Chromecast is HDMI only, ie. a 100% digital connection. You have to plug it into a HDMI-capable device obviously, but most people use AV receivers these days.
Besides, the onboard DAC in the CCA is more than good enough. No need to mess around with an external DAC.
So to sum up: * Bang for the buck get better audio quality * Still get all of the same Cast features (WiFi casting, group casting, etc.)
Hope that helps! :)