The MS8 sits after the factory amp in an oe interface situation or in use with an aftermarket headunit connected via preamp level rca connections or speaker wire.

Since you would not be feeding the unit 8 channels of input one of the input pairs can be used as an aux input from another device.

In this case you could run you sat radio in there and the ipod would be controlled by the MS8 via a hand held remote.

Or

By piggy backing the Drive +Play II into the aux you now have a more "ipod like" control **** and potential for bluetooth for your cell phone for hands free usage, optional sirus sat tuner box, use with other types of mp3 players ect.