@elizabeth is exactly right.
To take this concept further, the ideal setup of the service panel for cleaner audio would be to have your dedicated audio breakers grouped together at the top of the panel. Or at the bottom, if that's where the wiring enters.
So, if the lines enter at the top, your audio lines would be in the first breakers, same leg. Then the heavy duty appliances that you listed would be far away near the bottom split between Legs A and B. The theory being that the noise introduced into the panel would not be close to the audio breakers.
But, since the grounds and neutrals are shared, noise will still contaminate the rest of the panel to a lesser extent.
To take noise reduction even further, many audiophiles use a subpanel for their audio lines. This is a smaller dedicated circuit box attached to the main service panel.
When I expanded my system (which is very modest), I received step by step advise from our most experienced members on how to do this in my house. Now that I have a subpanel which has it's own ground and is tied to the service panel, the noise floor at my audio setup is extremely low. It helped in my case because I live in a prewar row home with a mix of old and new wiring.
If you had all new electrical installed in your home and the distribution of current draw is laid out well, you will be in very good shape with 2 dedicated lines. If you run that 2nd line, move it close to line #1 on the same leg.