I randomly see this number 19 in a red circle on both Tidal and Qobuz tracks. What is it signifying?
The number 19 in a red circle means that minors cannot listen to the music. If your Tidal or Qobuz account is not an adult account, you must verify your adult status to be able to listen to the music.
Okay, that explains it! Thank you! I’m 57, so I guess I’m safe. 
Thank you for the explanation. Thank you for my RS-520, I truly love it.