in my 2000 v70 i just installed a new amp and sub, tapping into the existing stock amps pre-amps under the passenger seat. I hooked the amp up straight to the battery so grounding isn't the issue. THe front right speaker will make a weird whine when i turn the head unit on if i turn on the dome lights it makes a different noise as they turn on. then when driving the speaker whines at different pitches with the RPMs. If i unhook the RCAs from the amp all whining goes away. Is there something i'm missing or doing wrong? the amp and sub were installed in my audi before it's timing belt broke, and there was never any whining and it was hooked up with almost the same setup (preamps off stock amp.)

 

well it turned out the website i got the stock preamp pin locations were wrong, so instead of having the RCA's have a L+ and R+ and shared common/neutral they were grounded to the front right speaker.. not sure how the amp still worked with out a - .. so then i cut the "negative" away from the front right speakers + line and just left it free. the amp and sub somehow are working fine without the neutrals on the RCA...

Not sure how its working without it as iv'e always had the idea that it should need both the + and - from the RCA preamps? is there any downside to having it wired this way?