I've been playing around with multiple setups with my AR3. Connecting PC's and other iPhones/Androids simultaneously to the unit via HDMI splitters.

My current setup is an iPhone 5S (docked) and iPhone 4S in the glove box with app ex installed. Both are connected via an HDMI splitter. All I need to do is switch BT connections to the iPhone I want to work properly on the head unit.

All these interface cables really are is just a way to charge the Phone. They have no functionality besides that. There is already a USB port on the back that you can use..

This USB port works for all iPhone setups

http://www.pioneerelectronics.com/PUSA/Car/Accessories/Smartphone-and-iPod-Cables/CD-IH202

http://www.pioneerelectronics.com/PUSA/Car/Accessories/Smartphone-and-iPod-Cables/CD-MU200

http://www.pioneerelectronics.com/PUSA/Car/Accessories/Smartphone-and-iPod-Cables/CD-IU201N

They are currently a complete rip off and waste of time with the AR3 unit.  

All you need to connect..

For 30 pin:

- 30 pin to HDMI adapter (apple branded)

- 30 pin cable for charging

- HDMI cable

For Lightning 

- Lighting to HDMI adapter (apple branded)

- Lightning cable for charging

- HDMI cable

For most Androids

- MHL HDMI adapter (Rocketfish)

- USB cable for charging

- HDMI cable

All touch control functions are transmitted via bluetooth with APP RADIO 3 decks. 

People say they could be used for some mysterious future functionality, but i wouldn't hold your breath. 

Usualy people who buy cables for tens of dollars are the ones that don't understand the functions of diffrent cables or how they work or what signals they carry, They just go by the manifacturer part #'s, Most of the cables are available at online auctions for few bucks if you already know what you need for your setup.

Got any links to these cheap cables?

I just use google, ebay, amazon, monoprice.......etc once I know what I'm looking for, for example if you were looking for a cable that you don't know the name and you were directed to here

A quick search for "short mini USB cable" you can get a cable that performs exactly the same for less than a buck here