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?

If you have mains that are bi-wire-able you will get a variety of opinions on how useful those extra two channels are. I love my 770 and just in term of number of components alone, if you are pretty sure you are going to go to 7.1, then I would say go for it just for simplicity's sake.

Since I've only got a Model 750 (although I may pick up a couple of 200's eventually), I can't speak first-hand to the sonic differences between the 770/755 and the 200, but there is a Model 200 review by someone who replaced a 770 with seven 200's and reported no sound difference -- so it seems pretty likely that you would not hear a difference between 770 and 755+200's. The 770 would cost you less overall and would use less cabinet space, but the 755 and 200's would spread the cost out. If you think it is likely that you'll go to seven channels in the not too distant future, I'd lean toward getting the 770 and letting two channels sit idle for now.

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gonk -- Saloon Links | Pre/Pro Comparison Chart | 950 Review

I actually purchased the 770 so at a later time I could upgrade from 5.1 to 7.1. It was a wise move for me since my cabinet was almost full and one box to do it all appealed to me. Not sure about the sonic advantages since I only own the 770. BTW, 7.1 is great!