Audio Systems: Mach 460 w/ aftermarket stereo on Mustang, sony xplode, mach 460

Question
I have a 2000 Mustang with Mach 460 audio. I recently replaced
the stock Cassette with a sony xplode. I have installed several
stereos before so this was no problem I thought. My issue is now
when I turn on the radio or cd-player there is a pop-squeel
sound like turning on a CRT TV almost. It seems most evident in
the front speakers. It only happens when i first turn the car on,
or turn on the accessory switch, or turn on the system. Switching
from radio to CD and vice versa there is no sound. Also if I turn
the car on with the player off there is no sound.
The wiring harness I used was the Metra 5511 to integrate the
460 amp to the sony. what might be causing the problem?
should i try to rewire it with the amp bypass harness or check
my wiring to the amp? It sounds awesome after that initial pop
sound, which is really annoying.

Answer
Without knowing the intimacies of your installation I cannot know for certain; my guess is the power amps are getting powered up before the audio head end is all the way up.

There should be a delay in the power amps so that the head end unit is all the way powered up and the votages have stabalized before the power amps come on...... or... alternatively, if there are relays in the speaker outs of the power amp, they are not waiting long enough.

So, you can go back and check for the delays and see if they are working or you can wire a seperate ON switch for the power amps and turn them on a few seconds after the front end/head end is fired up.

See what that does for you.  Let me know if you need more.
Hope this helps.

Cleggsan