Dedicated 20 amp circuit - Electrician laughed!

How much power do you need from the mains to justify a 20 amp circuit ? That would be equivalent to approximately 2200 Watts. Will you have that much power consumption ?

Unless you are coming VERY close to that number above, you will NOT hear any difference. The only advantage would be eliminating any possible ground loops if you plug every device you have into this one circuit. But then again, unless you really require that much power, you could gain the same advantage from just a standard 15 amp mains plug.

Extra power never hurts but will obviously cost.

I would ask if a 20amp dedicated circuit is enough? What is the total current draw of all your devices? 

How about a quality, properly sized U.P.S.? The correct U.P.S. will provide protection from Spikes, Sags in voltage, and filtering there by providing you "clean" power to any device you plug in.

In the normal mode most U.P.S.s would be running off battery and the line power will be charging the batteries.

One other thing to remember is "ground is ground the whole world round"

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
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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.