Power conditioning for multiple dedicated circuits

Take a look at the range of Audience power conditioners.  They have what you're looking for. And are sold by multiple dealers, some I'm sure with return policies.

@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?  

I think you've now protected your 12 wire circuits with a 40A breaker, which is a huge mistake.
That being said, wait for jea48 to answer.

Since this is a DOUBLE POLE 40 A breaker, each 12 gauge line gets it's own 20A breaker as you have already stated. Since this is a double pole breaker, that means that each 20 A side gets it's own phase as well. That is how your AC panel is set up. So far, I see this all to be an advantage, except for the shared ground and neutral. Not sure what limitations or problems that may cause, if any. 

I'm not suggesting power conditioners don't work- in fact, they may work effectively in eliminating more than what you intended.

True

Most of the ac mains "dirty power" found in our houses is caused by devices, equipment, and appliances, found in the home. Including the audio equipment itself.

As for dirty power put back out on the ac mains by the audio equipment, that is why more than one dedicated  branch circuit is used.  
YMMV.