How long will the wire run be? Pushing 200 Watts from your 770 I would say with a run up to 10 ft you could go with 16 gauge OK, for a 15 to 20 ft. run 14 guage, and 20 to 30 ft needs to be 12 guage. This is for a maximum power drop of .5 db over the given length of wire. For less power the guage could be reduced. System damping factor (including the empidance of speaker wire) needs to come out to at least 20, but the higher the better, so I would err to the side of bigger wire if it were me.