DMIMixer!

Use Your stereo USB AD Converter as a dual mono input and mix the two inputs in stereo. Just plug any compatible USB analog-to-digital converter to Your iPhone, iPad or iPod Touch* using the Camera Connection Kit and use its stereo inputs (left and right) as two independent mono inputs and mix two instruments with line level output into a stereo signal with level control and stereo panning. To use external microphones or guitars You should use a DA Converter which accepts microphone level input or use a separate preamplifier to get line level signals.