Johnslacker
I am sitting here reading your response and it is almost as if I swallowed five hits of acid and am trying to put this all together.
First off; now bear with me, what I am understanding is that you are powering a deck off a large power supply?
Ok check. the issue you are having is a harshness in your highs? Got it!
Now a few things, those white grey and green and purple wires coming off your head unit are powering one speaker each?
Correct?
There is no setting for ohms on the deck or adjustment of any kind so Im wondering about that statement.
Next, the power supply that should be hooked up to the red and yellow wires going to the deck is also powering another amplifier,
presumably running some subwoofers ; connected with 8awg wire to the power supply as well?
Ok lets troubleshoot this one component at a time.
First and foremost with that 8awg disconnected from the whole deal, and just the deck hooked up does your issue go away?
If so, the amplifier is exceeding the power output of that power transformer that your using.
It may say 800 watts output but that is a pretty exaggerated figure I am sure.
I could be wrong on this, but my understanding is that would maybe be the highest possible output at some ridiculous amount of distortion; say 25 percent.
Lets say thats not the problem, and the highs are still squealing like Ned Beatty in Deliverance.
With just the deck hooked up one at a time disconnect the speakers and see if maybe one of them has some issue causing a short on a tweeter maybe?
To test them with a ohm meter is the only real way to tell if they are in spec.
They should read 4 ohms on a meter, all the exact same.
Lets say they all do and the polarities are correct all the way around.
Positive speaker terminal connected to a grey with no stripe and negative speaker terminal connected to the grey with a black stripe for your left front speaker ect.
Next step I would take would be checking the settings on the deck and making sure they are all in the middle positions crossovers all set flat.
Did any of that fix this?
Lets see some pictures of this if you can not the components just the wire connections.
Hope this somehow has helped, interested to see what the issue was when you get it solved.
George D Gzhookupz
Do it movin! "I still have the Twindows modules from My 86 mr2 in the bottom of my box"