I would spec the receptacles at 20 amps if you still can. It gives you another place to plug in some low powered stuff if you need to. Also if you are going to use any type of protection gear in front of the amp it will draw some power.
At this point, I can still do whatever I want. I was gonna put 3 dedicated lines by my rack, 2 for the amp, 1 for everything else, but I can do 2 20 amp circuits also. Hell, I can put 3 20 amp circuits there if I wanted to. The beauty of it is I got a ton of space in my electric box, and the box is in the same room, so the wire runs are very short and simple.