I would like to be able to listen the same piece of music in more than one room as I move around my apartment. I have a 2nd gen. Airport Express that is fully updated, and a Medion internet radio with AirPlay support. I have an Amazon Music Unlimited subscription, and at this point there is still no option to select multiple outputs for a song from the MacOS version of their app. The same goes for Spotify. Why is it that the only music app on MacOS that allows multi-room AirPlay at this point seems to be iTunes???