Press play on either or both turntables and move the volume slider between the two. Scratch the records. Press the middle buttons for some classic sound effects.
To see how this is REALLY done, check out this one: http://wheelsofsteel.net/ (which I happened upon while looking for graphics for my version). CHANGELOG: Update: Cleaned up the code for the volume so that when it's in the middle, it's 50% volume for both, when it's all the way to the right, it's 100% for Turntable 2 and 0% for Turntable 1, etc. Update: Added the airhorn! And scratch effects when you click on each record Update: Improved the code more. Added color changing effects (very subtle). Update: Fixed the volume slider so it's always on top. Fixed sound effect button 2.