Liber said:
i don't quite follow... you're saying that they are quiter to create a source of sound? I just want equal sound from all four of those bastards.
You cant have it.
The reason is that you have 4 speakers in the front and 2 behind you. The speakers behind you are in a location that makes them almost non-existant as far as the drivers ears are concerned. The 2 high frequency speakers (tweeters) built into the dash angle sounds straight into your face. Then the 2 front door speakers provide decent midrange backup to the tweeters.
Its not that sound isnt coming out of yoru rear speakers, its that you just cant hear them.
You could adjust your fade settings to favor the rear slightly untill the sound blends, but I recommend completely ignoring it. Since turning up the rear speakers to match the front will either create unwanted distortion or just limit your potential volume for the front speakers.