complete audio overhaul

Hey guys I have a 2000 Celica GT-S that had the 8 speaker Premium sound. I started with buying a pioneer avh-4300. My left front speaker was blown so I bought Infinity Reference 6.5 Components in the front. I hooked them up without the crossover with the mids on the sub connectors and tweeter with the tweeters because the factory amp already had some filtering and I was told it would sound better this way. Everything sounded great and it got me thinking I could put another set of components in the back. So I ordered another set of Infinity components and also a KICKER ZX Series ZX350.4 - Amplifier - 4-channel, 4 gauge power and ground wire, monster 4 ch rca cables, 14 gauge speaker wire. So after the headache of running new wires, running power and amp turn on, installing all 4 crossovers, running rca cables. etc. etc... I power everything up and all seems fine at lower volume. I started to try and tune my amp for best possible gains. After playing with the settings on the amp and H/U, I have come to the conclusion I need help getting rid of this static fuzzy noise coming from the tweeters. I have absolutely no noise with the volumes low or off or anything like that. I only hear this fuzz (distortion) when volume is higher and I am playing music with a lot of symbols or treble. Music like Blink 182, R&B, Hip Hop. The fuzz sound can get very annoying at certain points in the song or stay fuzzy throughout the entire song. I am confused because I can play other music and it will sound crystal clear. I know the tweeters can sound way better because they were great up front when I had the factory amp pushing them. Please help me. Right now I have the amp high pass filters turned on, set at around 125 hz. crossovers are set at 0 db, and H/U has high pass filter on and set at 80 hz. I have tried all types of different settings so i'm not sure what is the best option or if this is the real problem.

playing your music off of an ipod or mp3 player? check the bit rate on your music, if its lower than 256 it will tend to make songs sound bad on an upgraded sound system.