Someone has been reading the a certain thread over on TA havent they ^^^
If you have been reading the 6x9 thread be careful what you gleam from it, there are about 5 different conclusions as to the use of 6x9's from that and TBH not one of them is wrong.
TA is a little difficult for the beginners IMO as much of the noob stuff has been covered a squillion times before and i have found that the members just arent that interested in helping noobs. (Not that i will say that over there again :bang
But back on topic for the OP low end 6x9's reproduce bad quality sound so although they can go very loud they sound like arse. Dont be fooled by 10000w watt ratings and crap makes like theloudest.com there 6x9's are actually (if they can even do that) 90w RMS (its all about RMS figures max means sweet FA) which is less than my tweeters.
Morel do good 6x9's but cost in excess of £150 which is about the same price as a decent set of components.
Even if you did put 6x9's to get anything like a sound stage (which really doesnt exist in a car but i will get into that in a mo) they would need to be perfectly matched to the speakers in the front of the car therefore you will have to tune the 6x9's down and you wont be using them to there potential and IMO they will still have an inferior sound to an equivelant set of components or even a cheaper set of coaxiles that wont counsel out the front speakers.
Any speaker in the rear will need to be sealed away from the air movement of the sub, Components are designed for infinite baffle so to put them in a sealed enclosure would be wrong, this is where i feel 6x9's may have a purpose because they do work well in a sealed/ported environment.
@ Gibbravo you have hit the nail on the head saying that you will never match the stereo image of home audio in your car and 99.9% of home audio stereo image is just wrong anyway compared to things like opera halls which have the ultimate in sound stage. So i ask myself should we really be worried about stereo image or shall we just balance the sound around the whole car creating a faux image
Sorry if that makes no sense i havnt got my literate brain on right now.