Question: iPhone 6 won't play with Kenwood DNX6160 stereo USB port.
I have seen a lot of forums with this same issue, and I found a fix to this without doing firmware, or buying a new unit, or anything. On the back of your Kenwood DNX6160 stereo, there is a head phone jack labeled "AV-IN". If you plug a headphone cord into there, and the other end into your phone, plus the USB cable, it will both show your music on the stereo screen and play through your cars speakers. I figured it out last night after 2-3 days of screwing with it. Good luck!!
iPhone 6s, iOS 11.2.6