rear fill? yes, typically just a basic pair of coaxials often using head unit power in an effort to provide sound for back seat passengers but still keep the "stage" up front.
Why would one not want to have good sound come from the front and the rear as opposed to the front only. I never understood this. It would seem to me that if the front sounded excelent, then an excelent front and rear would sound even better right ???
Ive been fighting the same situation. Here is what I ve narrowed down the the top 5 or 6 sets of coaxials (not in any paticular order but IMO, the JL's @ the bottom of the list). Course there are different opinions which ones will sound better. But uhhh,like I said, Ive been fighting the same situation for the past 2 Months at least! And just to let cha know, everyone will tell U its prolly not the best move for the coax, but if Ur gonna get some, definately get one of these. Good luck with the decision(s).