Dedicated line (almost)

I do not believe  you cannot cheat and get the majority of benefits. A direct line, takes the shortest distance between a breaker box and the outlet, it does not go wandering off and connect additional outlets (even if unused… these are sources of resistance), and is normally 10 gauge wire. The longer the run, the more likely it picks up noise.

So, a direct line is dedicated and direct, with thick gauge wire.

Do not know exactly the length of the circuit and the gauge. The breaker is 15 amps and the house is 10 years old so it is to new standards. Think I will buy a probe to try to follow the line and know better it's length and so on

Homes are wired so that’s single breaker has no outlets next to each other. But following them should be very illuminating.

A simple DC blocker ( Emotiva makes a good one) will take care of any LED or dimmer DC issues if you detect adverse hum coming from usually toroid core transformers. No impact to the sound from the speakers though.  Nothing more than a ferrite on a power cord is all that is needed for noise. Providing of course the equipment plugged in is not garbage. For protection of your equipment, a decent surge suppressor/filter is not a bad idea. Protection, not magic. Panamax, Isotrip etc. Even Monster made some decent ones.

I ran a line back when I had three modified Parasound 1200's and two subs. 10 Ga, 20A. I still had to run a Furman sequencer to get everything powered up as the surge was tremendous.  Valid reason for designed current draw. No magic. 

A lot of hub-bub is made about power by folks trying to sell something and folks who do not understand electronics.  I have no fancy power cords, dedicated circuits, regenerators etc. I can put my ear right to my tweeters, crank up the volume knob to higher than I normally listen to and guess what I hear?   Nothing. Not a darn thing. Black as black.   If you hear something, then track down your problem instead of grasping for straws. You can buy some really nice speakers for what an electrician costs. 

OH my gosh, terrible sound. Entrance cable is... ALUMINUM!   Can we get the power company to run a mono-crystal directional line from the transformer to our house?🙄

OP:

The proof is in the listening.  Do you hear a difference when the lights are out? :D

Erik