Trouble from ground distribution block

what about your power wire? are you running 2 different wires or one with a distro block to the 2 amps? and how close are your power wires from your rcas?

Good call, forbidden

Another thing to try is taking a portable CD/MD/MP3 player and hooking it up to the amp and seeing if you still get noise. You probably won't, and if you don't, then I agree with forbidden. But even without that test, he's probably right.

Here are some suggestions to help with grounding problems.

-Make sure you picked a good ground point for the amp, obviously.
-Make sure you scraped any paint off at your ground point for the amp
-Do the "big 3" wires under the hood (I use 0 gauge for it)
-Thicker ground for the HU
-Chassis ground the RCA at the amp side. Some RCAs have small wires coming out to do this.

If you're still getting ground problems, you can always run an actual wire for ground instead of using the chassis, but you really shouldn't need to do this.

There's a ton of info about ground problems on this forum. Look around.

The easiest way would probably be getting a set of RCAs that have an extra wire on the end for ground.

But first things first. You did run the RCAs on the opposite side of the power cable, right?

When one piece of electronics has a bad ground it goes looking for a new one, usually down the shield of the rca cable where it grounds to another piece of electronics and looks for a good ground there. This is where the ground loop and difference in groud potentials comes into play. This is sometimes do to how the equipment is installed and quite often the type of equipment that is used. What makes an item inexpensive for example, how's about inadequate circuit design. This manifests itself as noise in a system and sometimes it is all about the vehicle that the equipment is mounted in. Why I aksed about a Pioneer is simple, they have a piss poor circuit design and are breeding ground for noise. Pioneer builds these cd players knowing full well that they are designed for the masses and not the few. The masses use them with no outboard amplifers thus noise is never an issue, the few use amplifiers and when coupled with other items of say questionable quality, a noise problem can develop in the blink of an eye.

1) what are the amps grounded to?

2) what was done to the ground wire under the hood?

3) can you ground the cd player to the amps?

4) do you have a meter or are you installing using "the force"?

forbidden... using "the force" is the only way to install! :D

I like that.

I have to stick up for Pioneer here. I've never heard of them having problems with noise although anything is possible. 

I have installed several systems with Pioneer HUs and never encountered a single problem of any kind.

I think forbidden is right.  I read about this in the beginner MECP book.

Points where ground can run into a "loop" situation include:

1.  The low-level leads going from the output of a head unit to the input of a crossover or amp.  (Nothing will allow noise to radiate into a system faster than inferior cable with poor shielding.  Always use high quality cables.)

2.  An amplifier or any other component mounted directly to the metal of the vehicle.  (Never mount components to bare metal.  Always try to use an amp rack and insulate the other components from the chasis of the vehicle.)

3.  Grounding several components to chassis ground through their ground lines.  (Some preamp units get their B- connection directly from the interconnect cable - connecting the black wire to ground in this case causes an automatic ground loop.  Ground your preamp components to one point - usually the back of the radio - if their power supply ground is separate from signal ground.

4.  The antenna input.  (The use of antenna ground-breakers that are available on the market today is not a recommended practice, unless there is a severe grounding problem with a particular vehicle.  This ground is essential to the reception of AM.)

Although there are ground-loop adapters available on the market, they are really a "band-aid" approach for a system that should have been wired correctly in the first place.

The simplest way to avoid accessory noise problems is to never share a ground connection with the vehicle's accessory ground path, such as a fan motor or brake light ground.  It is highly likely that a pop or a buzz will be heard in the system whenever the fan is turned on or the brakes are applied.