Dedicated 20 amp circuit - Electrician laughed!

Also make sure the U.P.S.power cord / outlet are "twist lock".

In the old days there were 3 main ground sources that could be available in residential construction. I is not uncommon to use more than one should any source go open.

1. electrical panel ground which is most likely a metal cold water pipe comming from the street side of the meter with a strap around the meter.
2. a ground rod driven to the proper depth, also based on the moisture     content of the soil at that point.
3. attach the ground with proper ground clamp to a metal electrical conduit if grounded, on the outside of the home

Wow, Just....wow.
Ok, I don't really have the time to explain ALL of this. But to the "OP". 
Um, get a different "Electrician" please. And maybe call the local authority office  electrical licensing board. So they may have a "Talk" with him. :"That will be either a county or city specific office that has jurisdiction". Many times what many call an "Electrician", is not one in actuality. And many whom are licensed simply passed a "Code Test". And the quality of the knowledge base standards actually varies widely throughout the country. I found that almost all electricians on the whole do not understand the theories that guide what we write into the code. The NEC  is basically a Scope and a glossary with three other sections. Those three are simply- "Plan, Build, Use" and written in that order. No one explains AC theory, OR, DC Theory. It's not needed at that level. They also believe that, "Ohm's Law"? Is an actual set of what they see as, 
"The Laws Of Electricity"!!!!!
  Ohm's Law is a guide. Nothing more. For what "Usually" will work, NEVER "ALWAY" will ANY of it work. 
 Any of you fellows doubt me? I can tell at least a few here are working electricians. If your non-union call your professor from your "A" upgrade college classes and ask. IF union? Call the hall and ask. I am known at "Local 26" IBEW Washington D.C. and NOT hard to find.
 And it's nothing against any of you. You just never "really", studied the "Theory". "Yes I know "A" upgrade gets two years, One for AC, One for DC. theory plus "Abstract Algebra", IE,, "Boolean Algebra". It doesn't count guys. Anyway
.
Isolated grounding.....It works "IF" you achieve a "True Earth" ground with movement en masse. That's about the easiest way for me to unpack it.
 Dedicated circuits, They are great! Especially when you de-rate the copper and use "STRANDED" copper. Not solid. "I don't know why but "Siemen's" does". They talked me into it. and like everything else in this hobby? Yes, It will effect a difference in the sound of a rig given that it is indeed "Sensitive" enough to appreciate the change. And the "Room, furniture, windows and etcetera"? It becomes part of the "Rig". It all counts.

I agree with the electrician. If your amplifier and other equipment is built with well-designed power supplies, noise on the power line will be filtered far below audibility.

Furthermore, optimizing the last few feet of wire and connections from your service panel to your listening room will do nothing to affect the tens or hundreds of miles of transmission and distribution lines from the power station to your house.

If you can hear artifacts due to power line noise, blame your gear for poor PSRR, not the wire between your outlet and the service panel.

"IF", That last .001 of an inch of the copper conductor entering your equipment has it's circumference shielded, filtered, drained or in a few other ways modified. Then it WILL indeed,  "Modify" the magnetic field of said given area. Dependent upon "HOW" that field is modified WILL then give you a resultant difference in sound. It is an electrical system people. This is basic physics and Classic Electrodynamics, "for the most part". And some particle physics and a little field theory. Plus Quantum mechanics which then leads us into the realm of relativistic field theory. But, NOT the "Fuel line" on a 53 Buick!
 Just how did some of you guys accept the use of the microwave oven when it was first introduced? Oh, You hid behind the tree and peeked out until it was proven safe to use by that little girl and her mother. 
And not just bad, evil, "Magic" made by the "Witch 'o the North"?.........
   It's this new thing. 
We call it "Science". 
Get used to it. 
OR, 
Get out of the way. Go back and hide behind that tree again.