Our first upgrade will address the biggest shortcoming of all the stock BMW sound systems, BASS, or lack thereof. Use of an a/d/s/ AC502 remote subwoofer level control will allow us to control the volume of our subwoofer from the front of the car. How convenient! This way, we can match the bass level to our own personal taste or to compensate for bass masked by road or wind noise.

Source: www.bmwtips.com

Download PDF for this BMW 5-Series (E39) Audio System Upgrades Manual