So, I bought a new car stereo in September with a AUX slot so I could listen to music on my iPhone. That works great, for the most part, but I can't use the buttons on the stereo to control things. Only thing that works is the volume knob. Is there something I could buy to be able to use the next track/previous track controls... without buying a new stereo? This is the car stereo: http://shopper.cnet.com/in-dash-car-stereos/sony-cdx-gt320-radio/4014-6729_9-32747766.html#info-5 Thanks.