I put in 2 circuits so that I can put junk like switching power supplies for TV streamers on the other circuit. I put six outlets on each circuit. However, once you have a good poer regenerator, you'll find it is plugged in and most audio components are plugged into it. Mine has 10 outlets on it and all but 1 is full. Once you go down the high end power supply rabbit hole you'll need a lot of outlets.
I used 10/3 just as Erik describes above. This has the added advantage of giving you access to 240V if you have a piece of european gear.