Go Alpine or something good for head unit, after all it's the main hub for the music signal as such. Crappy quality head unit will make whole system sound balls, no matter how good the rest of set up is. And the other common term for "pre out" is "RCA's" it's basicly the out puts for the amps, good head units normally have 1 pair for front speakers, 1 pair for rear and 1 pair for subwoofer. Makes things easier to control from up front