How to guarantee to lower noise- ground loops in your system

Ground loops occur when the resistance between any two or more grounding points is high enough to cause enough of a voltage drop to be detected & amplified.

To reduce this:

1) Attach ALL your devices that handle signal circuits to a STAR configuration, ie to the SAME outlet/plug, with short mains wires. That is your turntable, subwoofer, amp, preamp, DAC, etc. If you do this, make sure you have a 20-30 Amp circuit to be able to carry the load of your megawatt amplifier. The more the better (and more expensive).

AND/OR

2) Use NON COPPER signal connections if you can (optical or fm/radio/wifi).

AND/OR

3) If you must use MULTIPLE outlets/plugs (no other choice), make sure the resistance of the EARTH connection between those 2 (or more plugs) is as close to ZERO ohms (the THICKER/OFC the wire the better) as possible.

If you do one or a combination of these, you will not have a hum problem.

In order to have a Dedicated isolated ground ,a plastic box does not qualify,read the link I included from experts a seperate insulated ground wire connected to the outlets then to the Copper
ground inside the breaker box. Nothing more to be said just ask a 
electrician

Service ground is the copper rod driven into the ground, typically right beside the house and very near the meter.

Nope. The Service Ground is the Powerline transformer neutral. The copper rod is for lightning protection. Many homes do not have a copper rod. They rely on the foundation rebar mesh [Ufer: https://en.wikipedia.org/wiki/Ufer_ground] or tie to the cold water inlet. Multi family building are an entirely different kettle of fish.

The 3rd wire ties in the panel to the Mains transformer Neutral [Center Tap] - the wider terminal. It is the earth safety. NO current flows in the Lightning Earth Safety rod when a fault trips a breaker.

Have a look at the drawing http://ielogical.com/assets/M-125/PTPolarity.jpg . It shows how ground currents can flow from transformer induced currents and poor inter-stage grounding. The lower section shows operation with power transformers in phase and a Loop Breaker installed. See https://sound-au.com/earthing.htm#s9 on Rod Elliot’s "Earthing Your Hi-Fi - Tips, Tricks and Techniques." UNLESS YOU ARE TRAINED AND 200% KNOW WHAT YOU ARE DOING, DO NOT MODIFY YOUR EQUIPMENT. The life you safe may be your own!

"teaching the Tubes4HiFi / VTA M-125 to sing" was an exercise in getting rid of ground loop hum. http://ielogical.com/Audio/VTA_M-125.php/ The amps are 40db quieter than delivered.

Adding a copper rod can make a system unsafe as the potential between the copper rod and the original earth can create a battery and eat away the rod. Acidic soils eat away copper unless there is a sacrificial less noble anode.

Additional rods must be placed based on their length and the effective length of the existing earthing scheme. Placing a rod willy nilly may increase the impedance and reduce the effectiveness of the earth lightning safety connection.

@millercarbon: Please do not pontificate on things that may make a system lethal.

If one were to run 10/2 romex (hot, neutral, and ground) and connect it only to one outlet and plug everything into that and then run that line straight to main breaker and land the ground on the grounding bar, does that count? Also, what is an insulated ground? Is that just a wire with a jacket as opposed to a bare copper wire?

From:
https://www.smartmetereducationnetwork.com/uploads/protecting-yourself-from-emfs/EMFs--Choosing%20Household%20Wiring.pdf

If wanting to wire a house for lower EMF levels, using the 3-conductor twisted ROMEX 12/3 (or any other suitable AWG size) is clearly a good choice. It is about ten times as good as the standard 2-conductor ROMEX wiring.