How can I use the sound from external applications in unity mobile and desktop?

Hi I was wondering how i can use sound from external applications that plays a song to be picked up in unity? Im making a Audio Visualizer and ive made it so far to pick up sound from the mic and change that to mp3 to be translated to the Visualizer. But my question is is there anyway to take the mic completely out of the equation and just use sound from the device so you do not have to have a mic plugged in. So in essence I want to have (for example) on mobile have the music app on a i phone playing music and at the same time my app open so it will visualize the music without it have to going out of the device through the speakers and back in through the mic because the visualizer than has trouble getting a loud anough sound and a good anough quality sound.... And By the Way im using Dastardly Bananas Audio Visualizer Thanks in advanced!!