Question about the Yamaha V661

[minorcomplex]

I know it's a 7.1 receiver, but I only want a 5.1 setup since I have a fairly small room I'm putting it in, so can I use it as a 5.1 receiver? I don't want the receiver to send the signals to two speakers that don't exist resulting in a whole lot of signal loss.

Also right now I have the 361, and it outputs 100 watts per channel at 6 ohms, but the 661 outputs 90 watts per channel at 8 ohms, so will the 661 sound better or worse when it's just playing the basic DD or DTS?

Thank you guys ahead of time.