I have a CMD 5 and I can use the Aux connector which allows me to use any external device via a headphone style cable ... you will need to control music from the Ipod itself in that method.
I bought the CCA cable from Crutchfield for around $60 and that allows the unit to charge (classic IPOD - 32 GB) and be controlled via the Clarion headunit ... this is definitely awesome since the unit charges and the head unit does all the heavy lifting.
I also run my son's Nano that way but it does not receive a charge via the cable. I recommend you read the compatibility section of the cable on the Crutchfield site .... using the cable also keeps my AUX input open for any "guest devices".
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