Power conditioning for multiple dedicated circuits

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. 

My apologies. I read right past the 40 A  and assumed the split  load myself. Yes, 20A is the correct size.

Eric, I always had an interest in doing just what you recommend here. In fact, I believe that the Richard gray Company used to make what was called the 'Power Station'. You give it 220AC, it uses a step down transformer, and produces 120AC balanced power IIRC. Of course it was massive and too expensive for me, but it did catch my eye.
 Long ago, I was able to run 2 separate 120 lines out of phase with each other, using some equipment on one line and other equipment on the other. That is why this thread appealed to me with the ganged breaker doing the same thing. Can't say whether or not it is an actual benefit to it, but want to believe that there some out of the box possibilities to be groomed from it.

jea48,

  Thanks so much for the explanation of using different phases of power in an audio system. Now that I have read it, the introduction of different power phases actually increases the chances for different types of noise. In my case, I am currently using one phase only to feed a BPT product which has 6 different secondary windings, each shielded internally in the transformer. I am satisfied with the result.