Audio Systems: Subwoofer Noise, solo baric l7, rca cables

Question
I am getting a rumbling noise from my subwoofer.  I thought it was due to the ground, but I sanded the area (GMC Yukon) under the floor panel and ran the ground there. Also I have had the ground mounted to the bolt for the rear bench seats. I have a Pioneer deck with a American Bass Pro 1400 watt amp, and a Solo Baric L7 (15). I have never had the problem beofre under until the ground wire came loose from the amp, and a spark came from the power wire. I'm thinking it might be the RCA cables because I disconnect it from the deck and I dont get the rumble noise. Do you have any suggestions on what it could be, and a better place to run a ground on a 2001 Yukon???

Answer
I cannot and will not go too deep into this because it is not a private question.
In a nutshell:
I would trust my instincts and try new RCA's ran across the interior as a test first and see where you are after that.

As long as you have a good, secure, chassis ground (and a short, large grounding wire) you should be ok as to the grounding location as long as the vehicle has no problems in its electrical system.

JM