I think you'll find the ipod earphone out is a 1.5mm stereo jack socket. It's quite easy to get an adapter to the next size stereo jackplug up which is I think the size used for computer sound leads, so then get a lead with one of those plugs on one end and twin phonos (RCA plugs) on the other. Turn Ipod down (those little suckers can chuck out nearly a volt!) plug together (aux input on the Cambridge or spare tape deck input), put gain on Cambridge about halfway and cautiously turn up i-pod.

If you are still overloading the input you will need a DI box.

Once you get it right you will start to hear the limitations of MP3 and MP4 compression!