Retrofit Subwoofer on High Performance w/o Subwoofer

[Lukas]

Guys, I am solving a similar problem on the xc40.  I have powered the front speakers in the door through an amplifier.  when I disconnect the connectors, no sound.  and during the test on the back door, no sound at all 4 and 5 on connector C.  just a faint hum.  also the center in the dashboard, number 2 without sound.