setting up two 10,s in the trunk with a amp using the stock head unit and speakers.. would the head unit put out enough power??

 

This will work. My husband did this in his F-150 SuperCrew with the factory stereo. He used 2-12" and a Rockford Fosgate amp. Not sure of all the wiring details, but I'm sure he'd post to help.

Good luck!

 

It's all a question of gain. Most (and this is a REAL general statement!!!) factor head units put out around .5V to their line level outputs. Some aftermarket amps can use up to 5V (or something like that), but almost all amps have a gain control (aka: sensitivity). The higher the gain is, the LOWER the input signal has to be to drive the amp to full power. You adjust the gain on the amp until you have it matched with the factory stereo and soudning like you want it.

Because line level outputs are voltage outputs and not really current outputs (aka: high input impedence at the amps), you can use one output to easily drive multiple amps with very little loss in signal strenght.

So the SHORT answer is that you should be fine with the factory head unit, but you will have to set up the amp gain to match it.