Hi, Im looking for any advice on a problem Im having with a new install. I've been installing high powered car audio equipment in my own vehicles for 20 years now but still consider myself a novice amature.

I have an Alpine CDA-117 with 4 channel signal cables running to a JL Audio XD600/6. I have the channels 1 and 2 bridged to 1 200 watt channel and channels 3 and 4 bridged in the same manner. Channels 5 and 6 are each going to each of my rear speakers. the 2 bridged channels are each running to each of my front speakers which are a MB Quart QSD 3 way setup (4" and tweeters in kick panels and 6" midbass in the doors). So the 2 bridged front channels are running from the amp and into a QSD164 2 way crossover. From there, the low pass speaker wires are running to the 6" Mids while the high pass wires are running to 2 way crossovers which split to the 4" and the tweets.

The problem Im having is I've got sound coming from each front 3way speaker set up and the left rear speaker only. No sound from the right rear. I'v egot a lot of buzzing and engine whine coming through. When I fade to the front, all the sound dissapears from all speakers except for the engine noise. The same happens when I turn my balance to one side. So basically sound is not being distributed correctly.

Now, when I dissconnect the left rear rca plug, I lose sound in my front door 6" midbass and the sound from both front tweets/4" mids is muffled and attentuated greatly. Also the sound from my right rear speaker magically appears.

So to me, it sounds like a ground problem, but my 4 gauge amp ground wire is tightly attached to one of my rear seat seatbelt bolt between the 18mm nut and the metal seatbelt clamp, which is pressed against the metal floor board. That nut is tightened down very securely.

My question for everyone interested in commenting is, does this problem sound like an obvious ground problem or a defective amp or head unit. BTW, the amp was bought from "Creative Car Audio" which is an authorized dealer. It is however a JL Audio refurbished amp with a 90 day warranty. The head unit was bought from a private seller as used then sent to Alpine to be repaired for an unrelated problem. Alpine corrected the problem and replaced several parts then returned it to me.

So thank you to anyone who can chime in with any advice or ideas as to my problem.