Romex and breaker switches


I did a search and have read previous posts, but I still have some questions. I had an electrician install dedicated lines in my listening room when we built our house 20 years ago. I bought simple hospital grade outlets from a big box store and did not specify the gauge of the romex or anything else. I need to clear out my dedicated listening room soon for new hardwood to be installed and figured now would be a good time to revisit and improve my dedicated lines. I have already bought a pair of Oyaide R1 duplexes and intend to have them installed side by side behind my equipment rack. My question is-is there a particular variation of 10 gauge romex that would be best? I have looked and there are quite a few variations including 10-2 and 10-3 and I have no idea what to buy or for that matter, if some other wire that would do the job and not be prohibitively expensive presents a better option. I will need a 20 foot run for each duplex. Also, can someone help me as to whether the breaker switch on my panel matters much and whether I should opt for 20A, 30A, or other? I now know that all runs from my duplexes to the panel should be to the same leg. I will make sure that happens. Any other recommendations or advice about romex/wire to use and breaker switches given my decision to go with Oyaide R1's would be most appreciated. 
fsonicsmith
Thanks to both of you for your responses. Yogiboy-the Oyaide R1 includes a specification that it will accept 10 gauge wire. I figured-perhaps wrongly-that using the lowest gauge romex or wire possible is potentially beneficial for current draw/flow. Both my amp (ARC Ref 150SE) and preamp (ARC Ref 6) draw a lot of current and for that reason presumably only accept a 20A component-side IEC.
I heard that a Synergistic Research employee fell into the Quantum Tunneling processor and wound up in Bangalore in 1932. Or at least he thinks it's 1932...
yogiboy0
You don’t want to put a 30A breaker on a 20A circuit.
Agreed! If you are using a 20A receptacle, you want a 20A breaker.

For a 20 amp circuit 12-2 romex would be the correct gauge to use. If you use 10 gauge it will be difficult to terminate on the outlet ... 10 gauge ( 30 amp ) is used for something like a clothes dryer!
There can be advantages to using 10 gauge wire on a 20A circuit, including reducing voltage drop. It is difficult to work with, and using a pigtail into the outlet does make it easier to terminate.

It's not all optional really. You can't use a 30 amp ckt without using a specially configured receptacle. It's no longer a "t" shaped neutral prong with a straight prong hot plus ground. It's shaped differently and your equipment would be unable to connect to it. And you can use a 10 awg wire on a 20 amp ckt but you couldn't use a 12 gauge wire on a 30 amp ckt. There's no limitation to how large your wires can be no matter the ampacity of a ckt. If it were me, without a doubt I'd install a 10awg 12-2 plus isolated ground bx cable. Hell, I'd definitely install an isolation transformer in the picture too if I were running a dedicated line. That would be a bigger gain than choosing 10 vs 12 awg. Pig-tailing a 12 gauge solid to a 10awg gauge solid wire is definitely not difficult.