+1
But I think I have found an option that is working to just cast the entire desktop sound (in W10), so that will do what I need - 2 clicks and all sound goes to the Wifi receiver while automatically shutting off the desktop speakers, then one click switches back. Right now I am testing with a LinkPlayer Wifi device, but I have a real Chromecast on the way for testing too. And since this app is sending the speaker output to the receiver instead of the raw audio file, it is not limited to any specifically supported audio formats. When I finally got the first successful test this afternoon, it was playing both wma and flac files just fine. But I have not yet done careful sound quality comparisons.
I do suspect that this may not work with a real Chromecast Audio, since the TuneBlade software I am using seems to be limited to using the AirPlay streaming format. Fortunately, there are a number of low-cost AirPlay wifi receivers available - I am testing the IDER receiver, available on Amazon for $37 (it supports both wifi and bluetooth). Now I have a low-cost way to effortlessly stream my lossless audio archive to my main system while using MusicBee as my chosen player, and that was my main goal.
Jamcast software supposedly will work with real Chromecast and other devices as well, but so far I have not been able to get that sofware to work.