As far as sound quality is concerned. Anytime you plug an ipod (as the source) into another component using the headphone jack on the ipod you will have inferior sound quality than if you plugged the ipod in using the connector at the bottom, which then gives you true line-out output. My understanding of the new BMW ipod/USB interface is that it does connect to the bottom of the ipod (and thus give a superior sound quality over the previous simple glovebox aux input solution) and the other end plugs into the new connector which has a 3.5mm jack for audio and a USB jack for power/data.