You need to search the forum for more inof. Depending on what options you have there are different ways to hook the sub. Mine is a non-DSP and so hooking the sub was very easy. I will send you a picture of the set up and wiring. I bought the amp & sub and had the stereo shop wire it up for $100.00
It's not that difficult but at the time I was clueless.

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2010 X5M /// R63 AMG...Wifey's 540HP Family Hualer

2001 X5 3.0i Sport 335,448 miles & counting...
SMG M3 Steering wheel
E46 Stainless Racing Headers
4.6is Exhaust
Turner Pulleys
Afe Intake
Brembo drilled rotors
PowerFlex Bushings
Hualingan
30mm H&R Spacers rear
20mm H&R Spacers front
Bavarian Autosport High-Performance Coils
Active Autowerke's Performance Software