Switching amp and speakers on stock stereo

[perk]

I have an ARC Audio KAR 400 4 channel amp (13x8x3.5") and Rainbow X-Plain 6.5" comps with tweeters and crossovers. Can I use these with the stock head unit? Could the amp fit under the passenger seat? How good will the sound be considering these components paired with the factory unit? If I want really good sound do I HAVE to scrap the factory head unit? I like the look of it and I like having the option of playing my old cassettes.

I'm hoping to add an aux. input to the factory unit from the center console, so I can plug plug in my Zune or Blackberry. If so, recommendations on which one? Right now, I'm using a cassette adapter; it works, but would like better connection and no wires.


Thanks,
perk

 

[jhrrld]

Video: JL Audio CleanSweep®

Something like this is what you would need. I'm pretty sure there are multiple options.