Dedicated line questions...

More is better? In this case more probably makes absolutely no difference and might even be against code depending on the wiring that is already in place. Unless you have an extremely powerful amp and very inefficient speakers there is absolutely no benefit in using a 20 amp circuit. Everything in the house goes back to the breaker box. Running a separate line dose not isolate your equipment from anything. If you have a noise problem get rid of the noisy equipment and get stuff with well designed power supplies that reject/filter noise correctly. This is audio mythology of the highest order. But, if you want to waste money on feel good ridiculousness that is always your option. 

If I were building a new home or re-wiring my home I'd probably run 20A to my audio receptacle.  But I wouldn't pay an electrician hundreds of dollars to convert my 15A to 20A without a known reason or goal.  I run all my gear into a power regenerator that only draws 500W and and 5.3A.  I have plenty of headroom.  It's all about what you're trying to manage and achieve.

 I believe running a dedicated line to the breaker box for my audio components only, will help isolate them. There are a lot of things that can create noise like the refrigerator and furnace, not to mention compact florescent bulbs. I have had problems in our last house with compact florescent bulbs in other rooms creating hum. We moved to a house in the country and I don't see us moving again. This is it. I now have a dedicated music room, so I want to get the best possible sound.

 I have been down the power re-generator path and have found it limiting. I couldn't plug my tube amps into it, so I could only use it for my front end. And after I got my Ref Phono 2se, I was going to have to upgrade. I couldn't have all my front end gear on at the same time. I sold the re-generator and bought a Shunyata Triton which is not power limiting. I have been extremely happy with that decisions.

The “goal” would be to get an over crowded circuit (11 receptacles, 4 light switches) off of the path. I have no other choice in terms of circuit or placement unfortunately. I pull off one receptacle into a Furman Elite for all my audio with the exception of my TT, but I might be changing that ASAP, so that everything is off the Furman. Problem with that is, I would need a 10ft power cable to accomplish that. But, given what MC mentioned and others, perhaps it’s not “worth it” so to speak. An SQ enhancement would be the bonus, not the end game.

@geof   That's a reasonable goal.  While I use a 15A circuit, it is dedicated to only my audio.