the zen connects at the oem amp behind the rear seat. its priority is to retain the oem functions while providing rca outputs. pac makes a harness for the first gen b&o (18-20) system however with the snipping of a plastic tab will also fit the the second gen b&o (21-current) however the pin locations are different and using that harness will give you wires for the headrest and overhead speakers. they are labeled incorrectly though. if you really wantrd to retain them, you will need an 12 channel processor and enough amps to have enough outputs to control those speakers.I agree 100%, I was just wondering if I used for example ZEN-A2B, would that remove surrounds entirely? Where does ZEN connects to OEM system?