Good morning, I am installing a Grom AUX1 onto the HU-650 in my 2006 XC70. There is a cable already plugged into the 8-pin port on the back of the head unit, I am wondering what that is for? I do not have the external 10-disc CD changer, and I do not have a factory navigation system. Is this port used for any other purpose? Incidentally, the GROM upgrade works fine. Thanks! -Mark