Probably more important to match the timbre and timing of the front left, front right and centre, than to match to the other surrounds, but I would try to ensure that the rears are the same impedance (ohms) and sensitivity (dB) at least. Not vital that they're the same brand or model at the front, but it's a better guarantee of matching timbre and timing, that's all. Most receivers come with their own sound equalization programs and microphone or you can adjust yourself manually. Personally I always seem to end up cranking everything but the front left and front right up 3 dB or more (i) because I like more centre to focus voices on the screen and (ii) because I like to hear the surround sound actually working, not just there asa background presence if you knopw what I mean.