Hot Wax DJ Player for iPhone and iPod touch requires a stereo splitter.

Here's a picture of an inexpensive one we like to use. The product is called an Audio Channel Separation Adapter. Basically what is does is split the stereo signal output by your device. This way you can plug in your headphones into into the LEFT output jack, and send the RIGHT to your amplifier or mixer. The product can be purchased from Circuit City at http://www.thesource.ca/estore/product.aspx?language=en-CA&product=2740396