When using the media shortcuts for play/pause, stop and next/previous they control the current active source. However, it is impossible to switch that source with a shortcut. It is therefore impossible to stop one player and start another one without direct interaction with the second player.

I would like to propose some shortcut to switch to the next media source. 
Additionally, a very shiny feature would be a pop up selecton menu on a shortcut (such as it is possible for klipper with the shortcut "open klipper at mouse position").

The selected media source should be also shown in the media widget. This would allow the user to display the current track of each media source and make the current selected source for the other shortcuts much more transparent.