Lowlander,
Thanks for the reply.
I happened to have a regular Chromecast lying around so I did some research.
The BubbleUPnP Server has the ability to define a DLNA renderer on a Chromecast or Chromecast Audio even though UPnP/DLNA protocols aren't directly supported on a Chromecast.
So I installed the BubbleUPnP server on Windows. Note this isn't a full UPnP/DLNA server. The media is still streamed by the MediaMonkey server.
Clicked the button to define the Chromecast client and voila, that renderer now shows up in the MediaMonkey Player options.
Clicked play in MM and sound and Album art are now "pushed" to my AV Receiver. With the Android MMRemote app, I can control volume, media selection, etc.
Reading the documentation, flac files are converted to .wav streams at 16 bit / 44.1 for the regular Chromecast. For the Chromecast Audio, it will support 24 bit / 96. Since the Audio is on sale now at Best Buy for $30, I will probably pick one up.
Life is good. Going out to the patio, sit by the pool and enjoy some tunes