Line driver questions

Was looking for some answers on line drivers ive read good things about them just unsure how to tie them into the system. If I have two amps running off two seperate pre amp out puts does that mean I need two line drivers one for each amp. Or is it better to find a eq with a line driver built in. Also can you send to much voltage to the amps by using a line driver? I hear of people using line drivers to up the signal of the ipod, is this done by running the ipod into the line driver into the aux inputs of the head unit? Is an eq with built in line driver and aux inputs for the ipod the best way to go wouldnt that take care of all of it? Sorry so many questions any help would be appreciated or any links that might help me out. Thanks