[NCBob]

Newbie here. Just ordered the BTA10100 for my 2012 Mercedes GLK350 with the optional Harman Kardon Logic 7 stereo. From what
I hear, everything from the HU to the amp in the rear is fiber optic. Also located in the rear, under two mats and a spare tire is a 6-7" double voice coil sub woofer. Because of its location, it is barely audible. That's why I ordered the 10100.
As far as power and ground, I'm good. I think.
What I want to do is hook up the FAST harness to the wires from the amp to the existing sub. Because it is a double voice coil, there are four wires going to the sub.
Can I use those wires to the sub and, if so, do I use all four or try to find which two to use?
Thanks
Bob