Quote Originally Posted by Nasir

The back speakers in my opinion can be much less critical as they are for effects only and I have used a variety of them providing their volume can be independently ( from the rest ) controlled by the amplifier or receiver.
Anyone who thinks the rear or side surrounds should be less critical than the fronts are not listening to modern day 5.1 or 7.1 soundtracks. As the mixer for Disney home video releases, I use 7 identical bookshelf monitor speakers and a sub. Every channel is treated as equal, because we do send very loud effects to the front as well as the surround speakers.

If you want to experience what I call the"sonic bubble", it can only be done with timbre matched speakers all around. This is also beneficial for multichannel music as well.