Audio Systems: Car audio set up, alpine cda 9807, alpine speakers

Question
Hi,

I have recently purchased a car, it came with a Alpine CDA-9807 CD/MP3/WMA/Radio receiver - 4x50 watts & 4v pre-outs.  Pair of Kenwood 6" speakers in the front doors (in original places), pair of custom fit Alpine speakers in the rear (again hidden away in the original speaker places).

The car also has a 10" sub wuth its own amp and a sony amp thats powering the front speakers.

I know nothing about stereo setups and would like to know if i need another amp anywhere or if this setup is wrong?

Answer
well there's a few ways of looking at this.  You say the front spaekrs are powered by the sony amp but the rear speakers dont have an amp?  I guess they powered the rear speakers off the alpine head unit?  Basically if you want to save a few bucks this is the way to do it.  you want the majority of your sound coming from the front speakers. The rear speakers should be turned down quite low so that they only give a little "fill" in the back but they shouldnt stand out at all.  so up front is where you need more power and using an amp is the right way to go.  so in the most basic sense your system should be fine.  the only thing I would say about this is you are going to have 3 problems but they may not bother you very much.  

one has to do with bass coming from those rear speakers, Ideally, since you have a sub, all the bass should be coming from just the sub.  bass freqencies have a habit of canceling each other out if they are not perfectly aligned so bass coming from your sub and speakers will not make more bass it will make worse sounding bass and most likely less bass overall.  depending on the features of this model (wasnt able to find out online) it may have a built in crossover,  usually with alpine you hold in the menu button for a few secs and you get the advanced features like X/O  (crossover)  you really should have the book to set it right but if you cant find it write back and I'll try to help with that.

the second problem is the phase issue between the front and rear speakers.  Ideally they need to be made at the same time so that you really hear just left and right.  if they are made at different times then the stereo image will be blured.   again turning the rears down will help dramatically with this and make it much less of a factor.

the third problem is that the rear speakers may distort first when turning the system up since they have less power available. this really shouldn't be a problem since, like I was saying, they should be turned down much quieter than the rest of the system anyway.  again that's something you'll have to find the settings for and tweak.

If you're still not satisfied with it after this I would not get another 2 channel amp if I were you, I would get a 4 channel amp since it will have less of the phasing problems that running 2 different amps would have.

Let me know how it goes!
Good luck!