HomePod Mini music source.

[DCM_UK]

Can anyone answer this question? When I enter my house my HomePods are on and presumably connected to the internet via my wi-fi and router. My MacBook is OFF, my iPhone is ON, I have a Spotify Premium account but not an Apple Music account. If I tap one of the speakers it comes into action, playing 'something', but where is that 'something' coming from? More concerning, if I go on to select and play a track of my choice, is it COMPLETLY replacing the original music, one would expect it too.
I am going to do a few experiments to see what happens if EVERYTHING is switched off when I tap the seemingly dead speaker(s).

 

[DCM_UK]

I can now confirm that I can source music from my HomePods with both my iPhone and my macBook turned off, the ONLY way the HomePods can obtain media is from Spotify over my wi-fi (I don't have an Apple Music account. One more test will prove this.