Shazam with SoundCloud?
You go into the Shazam app and you need to long press the Shazam logo until the "Auto-Shazam" words appear on the top of the circle. After that when you go back to your home page it will appear a red bar on top of your apps meaning that your Shazam will be listening to whatever song is going to be played. 

EDIT: It works with headphones of course :)