Need some troubleshooting assistance here. I have a Sony HU installed for a couple years now. From the HU I am using RCA outputs running a non-shielded rca cable back to a JVC amp. this amp feeds a 12" sub in the trunk. four speakers are then fed from the HU. Now I purchased another amp (50x4) to run the 4 speakers. I put the 4 channel amp in the trunk also. I ran a separate # 8 wire to the new amp and also another # 8 wire and grounded to the same point as the sub amp. I then ran two 4 cond. # 14 cables ( on the other side of vehicle not near the power wires) from the new amp in the trunk back up to the dash and tied all the speaker wires in there. Now to test I used the rca cable that fed the sub amp ( pulled it from the amp) and used it to feed into the new amp. Now, when vehicle is not running and I turn HU/amp on, there is a very slight whine but as soon as you turn the music up even a bit you don't hear it. However, as soon as you start the car, there is a god awful whine coming from all the speakers. As you accelerate it increases and decreases with speed. Funny thing is I never got any whine from the sub/amp I had. I tried running a separate ground from the HU ( i only had a piece of 22ga. wire and ran it back and grounded it to the same point as the other amps). This kind of deadened it a bit but not much. Any other ideas on how to solve/troubleshoot. Hoping it is not the new amp. I also tried disconnecting each rca wire individually to see if anything changed but it didn't. Any other thoughts on what to try. Maybe I should use the RCA for the sub amp and run the new amp with the high level inputs. At present the HU only has one set of rear out/sub out outputs so I will need to put a bunch of Y connectors in to split to go to both channels of the new amp as well as one channel of the sub amp. Presently I have no Y's in the system though. Thanks for the help!!