Is there an advantage to using a multichannel amp without all of its channels driven? I'm thinking of using the 755 for a five-channel setup that may expand to 7 at some later point. I'm just wondering if it might be an advantage to get the 770 now and not use two of its channels?

Also, I am under the assumption that the 770 and 775 are both superior (sound-wise) to the M200 monos ... judging from the specs. Any long-term auditions out there comparing the two?