Re: 2014 JGC limited 4 channel
Install it after the amp. The instructions state this. I've used the LC6i in Chrysler Alpine, and now using it in Chrysler Boston system. Since you have the Alpine system, you'll need to sum 6 channels in order to get a full-range signal to your amp. You'll want to sum the sub, front doors, and front tweets. If this doesn't produce a decent sound, substitute the rear door speakers for the front tweets. I had to do this in my Ram, but it had 3" dash tweets instead of 1" like the WK2. With the sub, front door, and rear door summed, this proved with best full-range signal for me. On a (minor) downside, you now can't fade much between front and rear. You may have to play with it a lot -- as these systems are a real PITA. I also had to move the GND jumper on the LCxi in order to eliminate a minor turn-off click after opening driver's door.
The LC6/7i are the cheapest solutions available. BUT, you may still want more. The summed signal requires a lot of EQ'ing -- as Chrysler Alpine/Boston like to boost treble, and have a real crappy signal to begin with. It could get real bright with your Focals. I'm wanting the DQ-61 now. My LC6i works flawlessly in my OE Boston car (0 noise), but I desperately need more EQ-ing ability. The DQ-61 would be a direct swap -- install would be a piece of cake.
2014 Durango Limited AWD in Granite: Premium Package, 2nd Row Captain Chairs, 2nd row Console.