Dedicated Line Noise Filter?

Not that it will help, but gotta say, @jea48 is just so generous with his knowledge- he helped me with some questions I had about an isolation transformer install, and I had a big electrical contractor do the work, open a permit, etc. There is a gap in knowledge, I think, between the electrician community and audio-- and jea48 gets "it"- no code shortcuts, but getting to the issues.
I’ll watch this thread with interest. I always learn something on these electrical/code/wiring threads.
What’s scary in Texas (unlike NY) is that it is caveat emptor for buyers. When we were looking at houses here, I’d say, hmmm, I wonder what the file says, and my broker would pull it, go to the city or county as applicable. Outbuidlings that were never permitted, additions, ditto. So, when you buy, it’s on you, the buyer. You may be ok until you want some work done, and then a city official comes by and says, "sir, that outbuilding there- we have no record of it." And you are in backwards compliance land.
I lived in PA many years ago, but have zero knowledge of practices there.
Good luck with this low-- you’ll get it sorted.
bill hart

@lowrider57 - @cleeds has it right- all "dedicated" means for our purposes is that the circuit isn’t being shared by other appliances, switches, lighting, etc. It reduces, but does not in my experience, eliminate, noise from other parts of the electrical system. My set up in NY (which was "permitted," but didn’t follow best practices I later learned), picked up noise from a low voltage light two floors away, and from various plug-in appliances, like a humidifier or hair dryer being used in another part of a large house. I also suffered from a nasty zap over the lines every time my tonearm  air compressor motor kicked in- this could have been eliminated by properly separating the lines rather than bundling them.

I guess the other reason why one would install a dedicated line is to be sure that you have no competition for current drawn from the same line.
I believe that the job done in TX in my new place is far better than the one in NY, based in part on the level of knowledge of the electricians, and my prodding with questions (some of which were helpfully answered by @jea48 along the way).