Haunz

iTrader: (3)

Sounds to me like you most definatly have a ground loop problem. Basically, signal ground at your amps is varying from signal ground at your headunit. This variation in reference ground is then amplified.

There are a few posible causes... first, to answer your question... yes, some amps are more prone to picking up noise... typically in the crossover section.... seeing as how the amp is made by legacy, that could be the problem...

Your RCA's may also be picking up the noise. I would recommend trying a plain twisted pair RCA. I doubt the amp in question has compairitive inputs (signal ground well isolated from power ground) to make use of the noise cancelling properties of twisted pair, but the loop area between the hot and ground wires is usually less then your typical RCA cables. (which helps)

My last thought is that you can try grounding your hu at the same spot where your amps are grounded... that way power ground between the two is the same... (Oh ya... someone said to disconnect your RCA and listen for noise... if it's still there you know this is the problem, or it's the amp - otherwise the problem is with the signal/rca's)

Good luck....

winner007

Thanx to everyone that reply me. I really learned a lot from u ppl. I will double check the ground and the battery. I let u ppl know what went wrong if i can find out.