Factory HU or replace it

I'm think about replacing my speakers and adding a amp but keeping my HU. I like the looks of the factory HU. The speakers are by Hertz or Focal and the amp is alpine. Please advise.

 

I just replaced mine with the Alpine CDA-105. You wont get the full potential out of your speakers or amp with the stock head unit, the output is not as high as an aftermarket one.

 

x2

 

If you have the money to spend on Hertz or Focal speakers, get a new deck with 4+ volts of pre-amp outputs. Those speakers will thank you.