Putting in a dedicated power line. 2 receptacles ok?

@theo

Both Line 1 (L1) and Line 2 (L2) alternate down each side of the panel. That’s how 240V load(s) can be fed from a 2 pole breaker.
Example:

Left side... Right Side
L1 .................. L1
L2 .................. L2
L1 .................. L1
L2 .................. L2


With that said the electrician may very well have fed the two 120V branch circuits from both Line 1 and Line 2. Easy way to check is with a multimeter. If both the circuits are fed from opposite Lines, legs, measuring from the hot contact (smaller slot) of a receptacle connected to one of the branch circuits to the hot contact of a receptacle connected to the other branch circuit you will measure 240V nominal. If both circuits are fed from the same Line,leg, you will measure 0 nominal volts.

You say an electrician installed the two circuits a number of years ago. Do you remember if the electrician installed Romex? Did he install two Romex cables or maybe only one?

IF only one Romex cable he installed a 120/240V 3 wire multiwire branch circuit. If that is the case you have two separate 120V circuits that share a common neutral conductor. The Romex cable will have 3 insulated conductors + a bare equipment grounding conductor.

If it is a multiwire branch circuit both hot separate circuit conductors must be fed from breakers fed from L1 and L2.

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@theo 
No worries, that's how I interpreted your post. And yes, as long as it works. 

Jea48, he did two separate runs of Romex. These are not directly across from each other as he did them about a year apart. Once I did the audio I decided later at a dealers advice to add the second circuit. And they end up on separate walls due to the room layout.

thanks Lowrider, my thoughts exactly. And the plus is I got to buy two AC conditioners. But if I move I will do it again, and hopefully while the house is being built so I can keep the two runs of romex apart from each other as well as the rest of the runs for the house. I have been told that is beneficial although I don’t think I will ever move. 

I do wonder if a 3rd circuit for digital would help, but no plans to do it in this house.

Well, you do the best you can! Good clean power has made a big differerence in how deeply quiet the background is for my audio experience. I use 3 separate dedicated lines for digital and analog power and source. The power in our little village almost seems like an afterthought on the grid - inconsistent, noisy, and frequently going out.

After trying all sorts of conditioners (the best to my ears was non-regenerating Sound Application), I decided to go to dedicated lines which are isolated and conditioned in the basement - just to get the box/cable out of the living space and because the big old industrial conditioner  I settle on hums a bit.

I have a 30A line to a subpanel with a noise suppressor/line conditioner in between. The lines are all on the same leg/side/phase. I followed some white papers from Vince Galbo (Plinius/MSB) to the extent I could anyway with some other tweaks along the way. I'm happy with the result. 

It's outlined on my system page here on Agon. I'm happy to share the white papers if you're interested.