Maybe a stupid MP3 player question, but here goes...
 

I've already removed the Bose amp, and run the HU into an LOC then an EQ into a Phoenix Gold amp (front doors) and Elemental Designs amp (for sub).

Why can't I just run an 1/8"-to-bare wire adaptor from my mp3 player spliced into the inputs of the EQ, and play my mp3 player through my system?

Sure...no steering wheel controls, and no fancy scrolling text messages thru the HU display, but also no $800 Phatbox hit, and I can still have SAT radio too.

It seems too simple, so there must be something fundamentally wrong with it. Please advise BEFORE I try it and blow something up.

Thanks!

You could run 1/8" to RCA converter out of the MP3, and run the RCAs straight to your amps (splitter used to run to both amps obviously).