My setup, PC (with a screen directly connected with dvi) ->hdmi -> hdmi splitter (to stereo and projector).
Now, the sound should always go out through the hdmi to the stereo no matter if the screen or the projector is used.
If I start the setup with the screen, the sound goes to the stereo perfectly. If I later switch on the projector, Spotify stops sending out sound, and I get "Can't play the chosen song" (translated from swedish sry if the code is not correct). The time tracker keeps on going, but no sound. All other sound is still working though (Netflix, Youtube, and so on).
It's not even solved if I restart Spotify, I have to reboot the computer and startup with the projector on.