A slider to fade between two simultaneously playing mp3's?

Greetings!

I have two mp3’s that will play at the same time. One is a beat, the other is the vocals. What I would like to do is create a lever that would allow the user to fade between the two. So if the lever is in the middle, they will hear the vocals and beat … right would be just the beat … and left just the vocals.

Would anyone know how to accomplish this or perhaps offer a starting point?

Thanks in advance :slight_smile:

Best,
J