Car Stereos: Speaker wire size, gauge wire, rear doors

Question
I am upgrading the door speakers in my '02 4Runner.  I am going with 6.5" components in the front and 6.5" 2way in the rear doors.  I figured I would replace the speaker wire while the door panels are off.  I was thinking that 14 ga. would probably be good, and 12 ga. while probably overkill, would be all I would ever need.  Then I started thinking; the wires coming off the head unit are much smaller than 12 or 14 ga.  

Is there any advantage to upgrading the speaker wires if the wires off of the head unit can only handle a certain amount of energy to begin with?
Thanks

Answer
Hi Chris,

If you're planning to continue using the head unit to drive the speakers, it's unlikely that larger speaker wire will make any audible difference.  If you're planning to upgrade to a separate amplifier, however, then a wire upgrade makes more sense.  

With that said, I'll note that a short run of smaller wire doesn't nullify the benefit of the larger wire.  For example, if your factory wire consists of 10 feet of 20-gauge wire, and you upgrade the size of the wire for 9 feet of the run, you'd still gain some benefit even though one foot of smaller wire remains.  This is because an undersized wire will lose power over its entire length; if you replace most of the length with a larger wire, you'd reduce the overall power loss even if some small wire remains.  The advantage is theoretical in your case, though, because the small wire is capable of handling the power output of the head unit without significant loss.  If the power output was higher (ie, with a separate amplifier) then the factory wire size would be more of a factor.

Hope this helps!

Brian