Dedicated Line Advise

I feel ya!   I live in Indy.  The heat from the eighteen tubes, plus the SS bottom end amp in my system, barely warm the listening room.  Then again, I am the only one in my house.   You might make everyone in your home dress warmer.  You know-  priorities and all that.

BTW- It doesn’t matter which side of the breaker box a 220V breaker is mounted on. It’s still connected to both phases. Your Electrician will know what to do, regarding getting your audio breakers on the same phase.  But- you might mention to him, you'd like the least number of appliances possible on that phase.

Lowrider - if your panel is like mine (i.e. a two bank North American panel ) - the adjacent switches in each "bank" of switches (i.e. if you have multiple banks) alternate between the two phases - e.g.

         BANK "A"               BANK "B"
Switch #    Phase     Switch #    Phase
    1                A              15           B
    2                B              16           A
    3                A              17           B
    4                B              18           A 
    5                A              19           B
etc...

For your two phase devices you will see a  "linked switch PAIR" which takes two adjacent spots - one switch of the pair is connected to phase A and the other connected to phase B (or vice-versa)

You need to make sure the electrician knows you require both lines on the same phase.

He/she should understand how to connect to the same phase

FYI - It only takes one two phase device to "pollute" both phases - so your goose is cooked - along with most other North American homes.

The only real protection against noise introduced by two phase devices is to get
1. an Equitech transformer $$$.
2. a power re-generator

I would not be too worried - unless the power in your area is prone to brown outs or surges, the noise from the furnace switch dissipates really quickly down the power-bus

Which switch bank is immaterial, but the farther away from the two-phase device switches the better

This link shows you a typical two-phase panel layout
https://www.google.ca/search?q=two+phase+house+distribution+panel+pic&num=20&tbm=isch&tb...

Regards...

forgot to add, the most noise you will hear from two phase motors is when they turn off and on, normally via a solenoid relay. Any more than that and I would co sider having the motor replaced - it's past its prime.

My furnace has a setting that runs the fan at a low speed all the time. so there is no switching as such and no high current spikes on the supply, which can cause a brief voltage drop, depending on your supply.

regards

One last thing - while you have the electrician there, get them to check all the connections and the state of the power bus.

if the panel is 40+ years old it might be worth getting it upgraded - all things oxidize with time and bad joints can aggrivate noise issues

That's it ! :-)