6x9 or 4x10
 

Have a 1994 full size blazer with the rear speakers in the ceiling. Mine have not worked since I got the truck and I'm looking to fix that. When I realized they were 4x10 I did some research and alot of people put 6x9 in there. My questions are; would there be any risk of damaging my wiring by running 6x9, or do they not draw enough extra juice to damage wiring. Also, would they even put out noticeably better sound without an amplifier. I don't plan to install an amp so would it be better to just get the best 4x10 I can find?

Not really much difference in them power wise so no worry of wire issues. Most quality sounding stereos have very little if any mid and high sounds coming from behind the front seats only lows (as in a sub). A good set of components up front properly aimed and powered and you won't even be able to tell that there is any speakers in the rear.

6.5" and make adapters