I know ideally all the speakers should be sonically matched and from the same manufactuer. My front three speakers are matched but how critical is it for the rears to be matched to the fronts. I just bought new right,left and center speakers for the front and would like to use my old speakers for the rear. These are all inwall speakers other than the center channel so it is not easy to test listen to the speaker until after the speakers are installed in the wall. Because of size difference I only have one shot at this.