If you want the best most accurate sound reproduction from 5.1 system, all the speakers should be identical. Here is the guide from the people designing the format
http://www.dolby.com/consumer/home_e...omlayout2.html
I would suggest that if you are concerned about the center speaker you could get a metal shield to keep the magnetic radiation from getting to the plasma BUT most of the manufacturers claim that Plasma is NOT affected by magnetic radiation.
http://www.plasmatvbuyingguide.com/1...oplasmatv.html
Sharyn