The 790 (at least the one we saw in New York last year, and I presume this hasn't changed) had two separate power connections - the only way to get 2100W of output is to have more than 2100W of input, and a single 15A circuit only offers 1800W. You should be able to connect a 790 to a single circuit, but you won't be able to max out all seven channels at once without two dedicated 15A circuits.