94 mazda mx6, new system

Hey to all. 

Here's my story.  So recently i got a pair of Infinity Kappa 50.7component system for my front speakers and some polk 5x7 db571 for the rear of my 94 mazda mx6.  After finally getting everything hooked up in the car i started the system up and started hearing alot of distortion somewhat scratchie from the tweeters but the audio was playing. Immediately i went back in and took of the front tweeters from the component system and found i had overlooked some things when wiring and wired the tweeters directly with the audio in. So after getting everything back and playing with the settings in my aftermarket radio(pioneer deh-p550mp) i found that while fading the sound from front to rear speakers i found that when i faded it to the rear all the way the tweeter distortion in the rear would stop but when faded to the front the woofers would cause some distortion in return causing distortion in the rear tweeters.  So while i was messing with all those setting out of nowhere all the speakers inside stop playing the headunit was still playing and i could hear the subs pounding in the back.  So after testing the speakers and headunit i figured it was the headunits internal amp that blew so i wound up getting a new pioneer deh-p400ub for starters, the music is on again and playing all around but i'm still getting that distortion from the tweeters in the rear when the music is faded more to the front.  any ideas on what can be causing this or i'm i gonna have to get a new set of speakers