Originally Posted by TayZ776
You would get plenty of power for 4 speakers just from a head unit plus if you get a nice head unit like pioneer you get Equalizers that enhance the speaker's sound. I would only get an Amp if i wanted to power some big subs or an extra set of speakers. But in theory, yes adding an amp to your speakers will increase voltage but its an expensive hassle and for the same price you can get a head unit.
not necessarily expensive. the amp i bought came with hi and low inputs.. so it easily would have went to my head unit. This means that i could have used rca (which i did) or i could have used the speaker wires coming from head unit to go to amp then to speakers. If cash is an issue (which it is for me) then look at some amps and make sure they are capable. I went with a middle of the road amp Profile ap1040 and it isnt a competition amp but it makes my infinity kappa's sound very nice.