I've got a Motorola E815 w/ a built in MP3 player. Does anyone know how to hook up the 815's player (which has a 2.5mm headphone jack) into the 3.5mm audio aux port? Plugging a 2.5mm to 3.5 mm adapter produces only sound from one channel. I assume this is a common issue for most cell phones w/ the MP3 player? any simple solution? thanks.