Power conditioning for multiple dedicated circuits

@kingsleuy  I used 12/3 Romex.  There is not a 2nd neutral wire.

Using Amps = Watts/Volts

On one of the receptacles there is my main amp(max 500 watts) and the preamp(max 130 watts).  This comes out to 5.3 amps.

Thanks, artemus....that is exactly what I was looking for.  I will give them a call and get their recommendations.  

I have been thinking more about my 12/3 wire configured for two separate circuits.  There is a single neutral and ground wire going back to the panel.  

Does this matter when all neutral and ground wires in a house are going back to their same respective bus bar?  The neutral and ground bus bars are even connected within the panel.  

I would like to understand how two of each returning the panel compare to a single run.

@jea48 I did the 2nd scenario you described.  I chose this because when I went to Lowes to pick up the Romex they had a bundle of 12/3 wire that was 1/2 price due to a return.  Therefore each duplex receptacle has 2 hot, 1 neutral and 1 ground.  I removed the hot wire's tab and wired to a double pole 40amp breaker so they each have their shared 20amp breaker but you cannot forget to switch one side off in the event of later work.  I did not research nor ask about this method so the only reason was simplicity.  What are the disadvantages?  I originally thought about using 10ga wire but got swayed by the wire on sale.  From your response I suppose sharing the ground and neutral disqualifies them from being dedicated.  What is the disadvantage for they way I have them wired?  

@jea48 I don’t have a problem that I am aware, but wanted to experiment in power conditioning. Many speak very highly and this would be new ground for me to explore.

I did not appreciate any change/improvement in sound before the new circuits either, but makes me feel better.  I also like being able to easily flip the 'music room' breaker whenever I leave the house for an overnight stay.