Found noise source. Help me find cure.
Here is my setup.
I have Computer ---> Panasonic DSP ---> Phoenix Gold Line Driver ----> Bose Factory Amp.
There is alternator noise and other interference (I can hear radio from noise). I have determined that the source of the noise is from the PG line driver. The problem is that i need this line driver because my DSP processor only output about 1V, so the volume is extremely low without it. Unfortunately this thing is a noise magnet. Here is how this line driver is making noises. The line driver has RCA inputs that is right beside the 12V power input. When these two cables comes close to each other there would be massive amount of alternator noise and radio interference. I have concluded that this is not a grounding problem, because i have tried grounding with battery, with harness, with chassis(right under the seats) and the result were the same. The only time there would be no noise is when the line driver is disconnected. So i'm looking for you guy's advices:
1) How to eliminate noise from the line driver.
2) How to shield my cables
3) How about a small capacitor?
4) Other things that worked for you
Tomorrow i will try the following: wrapping the signal wire around the power cable, and get better RCA cables.