This is actually for our Tahoe...and I have exhausted the audio forum guys for ideas on this one. I have verified my install as other amps work well with no noise, but the high end stuff, Zed amps), somehow is sensitive to the Tahoe, and causes lots of noise with key in all positions. Amps from my truck cause no noise in the Tahoe, and the Zeds work fine in the truck. So I have eliminated all other sources except possible interference...where can I look?

I was getting noise and the interference source was somewhere on the driver's side door sill. The cure was some graphite wire. Might want to see if you can isolate the interference. At least that is what worked for me. Good luck.

Make sure power and grounds are run on seperate sides of vehicle.(And grounds are on Good body panel or go right to the batery) I would not mess with it . Id get a new amp if your truck amp works in your Tahoe . It isnt worth messing with. You may have a bad factory ground, That is sensative to that amp . Or you can play the audio detective and rip apart a Tahoe !

A lot of electronic devices can cause intereference if they are too close. If you wires run next to those of another electrical device it is very likely that it is causing an interference. Check for good power and a good, clean ground. Putting some shrouding on the wires will also help.

It would be helpful if you could describe the noise...regular ticking sound? random crackle? steady hiss? 60Hz buzz? Is it definitely from the Tahoe or from somewhere close to where the Tahoe is parked?
Does it do it with or without music source connected?

You say it makes noise in all key positions. Temporarily connect amp direct to battery for clean power. Put key in 'accessory' position so as little as possible is energized. Start pulling fuses until noise stops. That will identify the offending circuit and will be a starting point to resolving the problem.

Without knowing more detail its difficult to troubleshoot from a distance.

I have verified all the grounds and am getting no resistence there. I did move the grounds around....run seperate, together, different spots, and no change. Power wires are the only thing running down the drivers side sill, and RCA's down other. Thing is I have run HU directly from battery, and run new RCA's through cabin to eliminate those sources. Noise is there connected to source or not, but not as loud. The sound is like a short wave radio that's not tuned in. Fuses....that's an idea I haven't thought of.