Anyone knows what the difference is between the $400 iPod/USB adapter and the $320 iPod interface adapter? I know the iPod/USB adapter is factory installed. I have a 2010 X5d on order to which I would like to add anything that would allow me to integrate my iPod into the car's audio. The car is now in 150 status so I was told nothing can be modified anymore. I do have premium sound and thus the 6 CD changer. BMW's website says "not with 6 CD changer" for the iPod interface adapter. Am I out of options; can't get the factory installed iPod/USB adapter nor the interface adapter? I would appreciate any additional input on these devices or any other options one has for attaching an iPod (other than through the auxilliary which does not allow control of the iPod from the car's audio). Thanks.