Another note I just found out is the 790 will also have two... yes that is right two power cords that will require two dedicated circuits. Wow!! This thing sounds like it is going to be one power hungry beast.
Pat Sklenar came back from the 2004 HE Show in New York with some
good pictures of the original Model 790 design (which was apparently sent back to the drawing board due to heat generation issues). The
rear panel photo shows both the 790's balanced inputs and the two power cords. Since the Model 790 is to be rated at around 300Wx7, basic math dictates two circuits to provide enough power - a single 15A circuit in a 120V system will only give you a maximum of 1800W of power (which actually ends up being less due to the nature of a 15A circuit breaker). Figure in the inevitable inefficiencies of an amplifier, and that leaves you a long way short of 2100W of audio power output.
My big question is, as a current owner of the 770, will the increased price of several hundred dollars over the current price of the 770 be worth it?
Personally, I can't imagine electing to move up to 300W per channels, so for me the Model 790 is just a curiousity. As for the difference between the Model 770 and its balanced replacement, I wouldn't choose to replace the original with the new solely because of the faceplate or the balanced input - but that's just me...