If you go by the nameplate peak power consumption on all of your components, two circuits would probably be preferred (one for the 770 and one for everything else). In general operation, a single 20A circuit would probably* be all you'd need, so it is probably not essential, but if your existing panel has space for two more breakers it would probably be a decent investment to go ahead and pull two at the same time.

* EDIT: I have enough faith in Hullguy's experience to upgrade that "probably" to a safe "certainly" .