2015 5-Series BMW The final system was tuned using our in-house curve. The remote knob for the subwoofer level was mounted in the storage pocket. The amplifiers were neatly tucked away in the trunk corner. The 6 channel VXi amplifier powers the front speakers. The xd amplifier was used to power the subwoofer. The Musicar enclosure was a perfect fit. Most all of the useable trunk space was retained.