Components
Phonograph is a music player that has a nice interface and many features.
Proposal
I want to suggest that the quit option should be implemented and added to the menu bar.
Mockups / Examples
This option should be the last on the menu bar as it is shown in the picture below 
Benefits
The benefit of the quit option is to totally disable any activity that was going on on the app as a back press will only minimize the app while it still consumes battery at the background.
Posted on Utopian.io - Rewarding Open Source Contributors