Interesting analysis. However, you are assuming that all 4 monoblocks are in the same outlet. In that case I would agree with you. Obviously, if they were on a different circuit then some benefit might be achieved.

Although, I must admit my curiousity is stirred. How could the 770 put out 2100W if it is only drawing 1800W maximum? Now bear with me, but if the total capacitance is sufficient then for some short time [t] with t<120ms [ milliseconds ] then it is possible for the 770 to do that. However, I believe if [t] is some long time in comparison say 10 seconds, then something would have to give. Of course, 10 seconds of a very high signal level in all 7 channels at the same time....not that much chance of happening.

Just my 2 cents worth, and I am probably missing something as well. Perhaps Gonk or Soundhound could help me out here?