[iq20]

Congrats on the new Soul first off. Your first question asking about running the power cable from the car battery or power port. I would definitely run it from the car battery using an amp wire kit, 8 gauge should work. That is the same amp that is in my Kia Soul. In my opinion I would tap into the existing subwoofer wires coming out of the existing amp to run back to the new powered sub or new amp and speaker.

As far as the two speakers you have listed. It depends on how much bass you want and money you want to spend. The JBL is nice and would be easier and cheaper, but less bass. The 12" Kicker will give you lots of bass, but you'll have to buy an external amp to reach it's full potential. The JBL will save you room, the Kicker will take up more room. For either of these you'll want to buy a Line Output Converter (LOC) for the RCA cable hook up from the existing amp to run to a new external amp or the powered sub.

If you decide to go with the 12" Kicker you'll need to get an amp that is 2 ohm stable since the speaker is 2 ohms. 2 ohms is good, it creates a lot of power.

I would recommend buying from Crutchfield if you are not to knowledgeable on any of this. They have good support. But with the interwebs you can figure anything out with enough research, that's how I learned. I'm still by far an expert, I'd say a little above novice.

 

[iq20]

If your kia amp wiring is the same as mine, which I believe it is, this should be easy. Connector A (white) is the output to your speakers. Connector B (black) is the input, you'll only use wire 6 on it. On the white connector pins 5,6,11 and 12 are your existing subwoofer wires that I would recommend. That's the wires I tapped into the second time. The first time I tapped into the rear left and right and my subs were getting to much high freq and it sounded horrible. Your JBL has RCA inputs and a high input power connector (HIPC). To avoid buying an LOC you could hook up your JBL using the HIPC. For the splicing into the kia amp wires I would recommend using the solderless quick splice snap wire connectors. You can buy these at Walmart. I'm hoping your connector wires are the same as mine. I take no responsibility if this burns your JBL up.

From you JBL you'll run the HIPC speaker wires and ground wire to the kia amp, depending on where it is, mine was located under the front passenger seat. I unbolted the seat and leaned it back to make it easier to get to the kia amp. Run the HIPC +12V (red) wire to your battery and hook it up to the red terminal, making sure the 15A fuse is in line. Back to the kia amp, wire the Ground (black) wire to the chassis some how. I unbolted one of the kia amp bolts and wired the ground onto it. Now wire the Remote (blue) to wires 6 (ACC) on the B connector (Black). The only wires left on the HIPC cable should be the two lefts -+ and the two rights -+. I'd wire the left - to wire 12 (Subwoofer 1-), left + to wire 6 (subwoofer 1+), Right - to wire 11 (Subwoofer 2-) and Right + to wire 5 (Subwoofer 2 +) on the A connector (white).

I hope this helps. Let me know how the JBL sounds. My next upgrade will be the front and back left and right speakers.

Heres the link for the kia amp components. Kia Soul: External Amplifier Components - Audio - Body Electrical System

 

[iq20]

Sorry for the late reply. I’m hope you figured it out by now. That picture of your amp there is different from mine. I looked around on the internet and I couldn’t find a wire diagram for it. It is strange that yours is different than what the online owners manual shows.