A/v Receiver Only 2 Speakers How Do I Use A 7.1 A/V Receiver With Only 5.1 Speakers?

How do I use a 7.1 A/V receiver with only 5.1 speakers? - a/v receiver only 2 speakers

I have a 7.1-Receiver with 90 Watts per channel. My 5 speakers have an output of 150W. Can I have more performance out of my 2 unused channels play 5.1 setting?