This one has been bugging me for a while… Spotify on my Mac stops playing as soon as the screen goes dark (due to power saving mode). Seems to happen regardless of audio settings or Spotify settings.

Apparently it's due to a hidden "App Nap" setting which can be easily fixed via the Terminal:

defaults write com.spotify.client NSAppSleepDisabled -bool YES

IMHO should really be exposed in Spotify's preferences.

Thanks to this post for the solution.