Time for dedicated outlets!

perazzi28 is correct. #12 wire is rated for 20 amps and #10 is rated for 30 amps. If you use a 20 amp breaker it will trip at 85% of rating so what is the point of going to #10. Run a 12/3 romex that is a neutral with two lines and a ground. This will give you two dedicated 20 amp cicuits with one run. Same labor cost. By the way lots of us in the electrical fields are also audiophiles.

Jea48, the bare wire is the ground. It is connected to the ground bar in the panel and at the outlet it is connected to the box and outlet ground screw

Cleeds, that is true. If the run is 50 feet or more you should use # 10. If 100 ft  go to # 8.

Baddoge, if u have four breakers u have four circuits and u did not get that with 10/3 wire. 10/3 wire has 2 hots a neutral and a ground and is good only for 2 circuits. You must have run more wire

Jea48, The NEC does not clearly define that and it is left as a design perrogative. It is understood that a dedicated circuit is one where only one appliance will use that circuit. A neutral can be shared but only one appliance per breaker. Some elect to run a neutral for each as a design choice. In either case the neutral is run back to the panel and attached to the neutral bar where all the other neutrals are.

Also you would not connect to a double pole breaker, that is for 240 vac here in the US . They would connect to single pole breakers as they are 120 vac. 

Why eould you not use the bare wire for ground ? That is its intended purpose. In romex each circuit wire has insulation and the ground is bare and all of it is in a protective sleave