Before I start going through the troubleshooting list since there is noise with the radio turned off I was thinking there might be a quicker answer. Here goes, my brother had his system installed a couple of years ago in his VW "something" I think jetta but it worked fine the whole time but a week ago all of a sudden there was noise with the radio turned on or off using the turn signal, winsheild wipers, rpm, pretty much anything electrical coming through the speakers with radio on or off

like Lelu please help

Check your grounds and other connections. Something may have come loose.

I always find it best to do as much troubleshooting you can then come for help. That way, we know what you have and haven't tried. A lot of times, the problem is just something silly that can be figured out pretty quickly.

check you gains also bass knov all those knobs in your amp turn them down a little bit

Now thats odd, you said there is a noise in your amp with the radio off? Is this with the car still on, why are your speakers receiving a signal with the radio being off?

what's your headunit?

IIRC certain Pioneer headunits have Pico Fuses on the RCAs, if blown they will cause lots of noise.

Is there a mid/high amp in the car?

If you have an amp, see if it is turning off when you turn the radio off.. (like its supposed to if you hook it up right) but whoever put your amps in may have tied your remote wire into the vehicles accessory power wire. If this is the case, your amp is still on and you have some sore of problem with power wire ran too close to the rca's, bad ground, or bad amp. Unplug the rca's while it's making the noise and if it stops, then you know you have a problem with your rca's. If it doesn't, the problem is with the ground/amp.