Originally posted by igo4bmx
the reason i say no rear speakers at all are for a couple different reasons.
1- your car plays STEREO music. stereo is played in a two channel signal (right and left). so 4 speakers would be redundant right?
2- when you listen to a band for example, sounds come only in front of you. so why would you like to hear audio coming from behind you? this would ruin the potential good imaging you can have in a car.
3- along with the imaging. have the four speakers would be hard to time align them or make them plausible to your ears. sound travels at a certain speed (i forget how fast) but so with that idea, the rear speakers hit your ears after your fronts do. higher end head units try to combat this with time alignement.
i don't know about your first 2 points, but for number 3, the speed of sound is about 340 meters per second. Considering you are like 2 meters at most away from the back speaker, i doubt any human ear could tell.