Outlaw's tech support may be better able to answer this one. My electrical background is somewhat basic, but from what research I've done I think that part of the question here will become "how is the amp (or amps) being provided with power?" A single 15A circuit dedicated to the 770 or a stack of seven M200's will impose a limit on how much output will be available. If you had two 15A circuits dedicated to the two stacks of M200's, you might be able to get more out than with a 770 that has its own 15A (or 20A) circuit.

Based on some discussions that have occurred here in the past, a single 15A or 20A circuit does not offer enough current to allow a solid state amp to produce 1400W (inefficiencies - which produce the heat we are all familiar with - take a significant share of the input, which on a 15A circuit is limited to 1800W). The reason that a 200W/channel multichannel amp like the 770 still works is that the channels with the greatest demands on them (mains and center) may have transient loads reaching 200W each, but the other four channels typically are significantly less loaded, making it unnecessary to have all channels driven to max at the same time. (As an aside, the planned Model 790 will reportedly be able to achieve 300Wx7 with all channels driven. It, of course, has two separate power cords, and to achieve 2100W of output it would presumably require two dedicated 15A outlets to draw from.)