I have a 8 yr old EL10 amplified Bazooka (I think, all the writing is worn off). I just got a new wiring harness cause my ground pulled out and now when I plug in both RCA's the sound is very very muffled. I tried reversing them but it doesn't work. When I plug in only one at a time it seems to work fine. It doesn't matter what combination I use as long as only one RCA is plugged in. Will this hurt my speaker? If so, can you suggest what I might have wrong? I have a factory Mazda stereo. It worked fine with both the RCA's plug in prior to the new harness.