In my box of miscellaneous shit, I found a miniUSB to USB A cable, so hooked up to the USB HEC to my iPhone via the camera adapter. To my surprise (and complete delight), the radio still controls the track up/down, but the HDC3 controls volume and sub. I can change tracks with the steering wheel controls, but not volume...and the "now playing" info and album art displays on the headunit. I can only assume the radio is controlling and communicating with the phone via bluetooth. The only drawback with going directly digital to the Helix is I can't use the phone because the audio part is bypassing the radio, so it will be great for demos and critical listening, but not practical for everyday use.