So I just pulled a u310bt out of my car and put in a used f700bt that I got really cheap off of ebay - it did not have the a/v harness included.

The u310bt plays audio from ipod/iphone just fine over usb without additional need for separate a/v lines.

Does anyone know if it is even possible for 700/900 to play audio over usb? Is this something in hw or in software?

A driver/dll perhaps?

You need something like this http://www.amazon.co.uk/RCA-Composite-Cable-Apple-iPhone/dp/B003VQX6FQ/ref=sr_1_1?ie=UTF8&qid=1326659155&sr=8-1 - this is the pioneer one http://www.amazon.co.uk/Pioneer-CD-IU230V-interface-connector/dp/B0017PGTF2/ref=sr_1_1?s=electronics&ie=UTF8&qid=1326659454&sr=1-1 - and the pioneer AV1 cable.

Audio uses the red & yellow phono connectors and video uses the yellow one - I think USB is used only for command & control. Make sure you get the right RCA cable for your model of ipod/iphone

thanks i had the same question. i have a single DIN cd player for one of my cars that i just use the IPod data cable to listen to music but the AVIC-F900BT needs that special cable..... thank you thank you thank you