
The AUX interface of the BMW E39 is located in the armrest box on the right side of the driver's seat. The AUX interface (Auxiliary) refers to an audio input interface that can connect to electronic audio devices, including MP3 players, allowing the car's sound system to output music from these devices. In some models, the AUX interface can both input and output audio, while in others, it can only input audio. How to use the AUX interface: First, prepare a playback device (such as a computer, phone, or MP3 player) and a single 3.5MM audio cable. Then, plug one end of the 3.5MM dual-head cable into the headphone jack of the phone or MP3 player, and the other end into the car's AUX port. Once connected, turn on the car's media player and switch it to AUX mode, then start playback. Note that the AUX interface is different from the USB interface. The AUX interface can only connect to external audio devices for playback, with the car's audio system handling the power amplification. The USB interface, on the other hand, offers more functionality, allowing connection to various external devices for data transfer, file copying, etc. However, in terms of audio playback quality, the sound through the AUX interface is better than through USB. The audio quality of AUX is comparable to that of a CD.


