To eliminate potential hum, tell him you want the circuits on the same leg. Your AC coming into your breaker box consists of two hot wires or legs, a neutral and a ground. If you measure the voltage between the two hot wires you will get either 220 or 240 depending on the power company in your area. Measuring between either hot wire and the neutral will give you 110 or 120. You want to make sure that both breakers for your dedicated circuits are attached to the same leg. Also, when your electrician is connecting the outlets, make sure he uses the screw terminals and not the backwire terminals. The backwire terminals have a very small contact area and could cause problems. If he wires everything up to code then you shouldn't have to worry about grounding. I have heard some audiophiles insist that the ground wires be side by side on the ground bus bar in the breaker box. I'm not sure of the reasoning, but you may want to have your electrician do that just to cover all the bases.
Hope this helps
Hope this helps