I do not think you have the aux input. Did your X5 come with the in-dash CD player or cassette player? If it came with the cassette player a cassette adaptor is a very valid solution for connecting an mp3 player. I installed one in my X5. I managed to pass the audio wire behind the radio, inside the central column and up to the central arm rest where I have my mp3 player. There is no visible wire and the sound is great, as good as from a CD I would say. You have to make sure that you pick the right cassette adaptor though since some have noisy wheels
Here is the related thread: http://www.xoutpost.com/showthread.ph...assette+player