What about the situation of most homes in the US, sharing their pole or ground mounted power company transformers 240 volt output, with as many as 3 other homes power drops ?
In my case, I share the split phase 240 volt output of my across the street pole mounted power transformer with my either side of me neighbors..
I can run a electrically clean & low noise house and use dedicated 20 amp circuits for my house`s systems, but without good power line filtering/conditioning at the audio system`s location, either neighbor could easily pollute the shared power drop, by them using a welder in their garage, or a noisy tower/laptop SMPS, microwave, etc.
So my point is, you can have a great local dedicated power circuit, that still might be noise polluted from being in a sense, directly connected to your neighbors, using of that same power line phase with whatever dirty electrical devices they may choose to use, or have automatically running, and that "quality" power conditioning on sensitive audio equipment power circuits might be a wise & beneficial investment, it has, and is for me.
Just a thought.