I wouldn't let that guy near my car. That electronic part is an LOC (Line Out Converter). This part will take speaker level audio and convert it to RCA level audio. This allowed him to put an aftermarket amp in your car not a BMW amp. Also that part is not a BMW part. I don't think BMW makes any LOC components as they don't need them. You must have a BMW amp to get DSP.

__________________
[Sold] 2004 X5 4.4i - Sterling Gray - Truffle Brown, Sport, Preminum, Rear Climate, DSP, Sirius, PDC, 132's (19 inch wheel), Comfort Seats
Dynavin, JL Audio Stealthbox, Alpine PDX-5 Amp