do you feel weird when you go to a concert or show and not have anything behind you?
if you look at a frequency response cjhart for these speakers, you will see that they have some major breakup in the lower midrange. they are NOT MEANT for play above 3000 hz. if you do not have an active crossover - or a specific passive crossover for them, sound quality is not for you.
they are meant to play from ~60hz to ~3000hz - if not lower on the top end.
nothing else.
and NOT from behind you.
they are not subwoofers. they are not midrange speakers. they are MIDBASS speakers - meaning that they should be up front with your front speakers. the aim of "STEREO SOUND" aka: LEFT+RIGHT channel recordings aka: NON DOLBY DIGITAL music aka: 98% of music recorded by normal artists is to EMULATE A REAL CONCERT EXPIERENCE
that means the music should have a defined CENTER, LEFT, and RIGHT channel - that comes from IN FRONT OF THE LISTENER. ANY fill from the rear of the vehicle will pull the sound twoard the middle of the car and screw it all up.
THAT is sound quality. if you are not going for sound quality - do NOT claim you know what you are talking about.
if you put those speakers in your rear deck, and i ever meet you, id like to give you a swift kick in the nuts.