I want create an mp3 player that can play aac's and output to 4 speakers.

(for Car audio)

Any idea how this might be possible ?

I found a very nice IC for mp3 decoding it's called:
VS1033 this can decode acc's and wma as well, and all this at 320 bps

But it decodes acc to 2 channel audio

99% that i will use this chip in my project, witch interfaces whit an
already professionally produced car audio CD player (KENWOOD KDC5070)

I will completely remove cd player and replace it whit my custom built
mp3 player, only need to solve level differences, for the audio levels
of the original cd player and the above chip.

Currently i am having some thoughts about what micro-controller i
should use. Would probably go whit atmega 16, but if i could find a
developing platform and cheap IC's of a 32 bit microcontroler, so i
could incorporate additional functionality, Thinking about changing
LCD display to graphic one, and displaying more info then just what
music is played, like what's the inside or the outside temperature..
and stuff...

First things first. I need to decode and analyze comunication between
the 2 mc's of the KENWOOD KDC5070.


One might ask, why i am doing this... To learn :D and for funn.