What does 5.1 or 7.1 surround have to do with bi-wiring, I think your confused on what bi-wiring and/or bi-amping is all about.

This is a good introduction by Alan from Axiom. If you read the entire article you will see that some 12 gauge wire by itself will do just fine. It appears that lab tests have also shown very little difference if any.

http://www.axiomaudio.com/tips_biwiring_and_biamping.html

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