if you want SQ or SPL. SQ is where you use four channels in which speakers are positioned at all four corners of the listening space,(i.e. car, 2 in front, 2 at the back or for some 4 at front and a sub woofer at the back) reproducing signals that are independent of each other. here you have just the right amount of sound for listening pleasure. or if you want SPL like if you have watched the movie fast and the furious (the ones that are so bassy but with a crisp sound.) it depends also on the head unit you choose. for me i choose alpine which i think has the best to offer with regards to wattage and channels. seperates are also another thing which would define the voice in the music. tweeters can also help for that "life like" sound. then the sub woofer which would give body to the sound. my choices of speakers are targa, crystal or kicker, and for the subs kicker or targa. but it depends really on what u prefer as i have mentioned above and also your budget. 2DIN or 1DIN is basaically the size of the head unit. depends on what car you have.

HTH.

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