If you use any multi-zone receiver with Spotify Connect or Airplay, you are probably already frustrated with the fact that when you try and use Spotify or Airplay to the second or third zone only, the main zone switches across to Spotify or Airplay!
This is a limitation of both Spotify and Airplay, where they only see one device on the network, not the two zones separately. This issue is common to Yamaha, Denon, Marantz, Pioneer and all other major AV Theater Amplifier Manufacturers.
There is no easy software fix. Your only real option is to add a separate Spotify or Airplay source for the extra zones. For example if you use Spotify, add a Chromecast and rename it Zone 2. If you use Airplay, add an airport express.
"Your only real option is to add a separate Spotify or Airplay source for the extra zones"
If your amplifier can decode Digital Streams into the extra zones (like the Yamaha RX-A1060 and above) you can even use the optical digital connection for the best sound quality in these zones.
Your other option, is to use a separate MusicCast component (You can see our MusicCast Range Here) for use in the extra zone. Because there is an extra network tuner in each device, each component shows up as a seperate device in the MusicCast App and can be streamed to directly