When “grounding” an audio system, the first thing that audiophiles do is make sure that their AC receptacles are in order. This is a great first step! It is vitally important that the AC line and load wires on all receptacles being used in your hifi system are correctly phased and properly grounded.
However, if you really want to address earth ground, the most practical and worthwhile upgrade is to install a dedicated circuit for your audio system. This step should be followed by installing a separate, external ground path to an external ground rod. Each of these solutions provides a path out for unwanted, “spurious” currents that circulate through the circuit and add noise to the system. Unfortunately, these measures ONLY address earth ground, and don’t do a thing to address signal ground.
Signal ground becomes a problem whenever currents are generated during transmissions between devices in a system as a result of the small differences of potentials in those components. In order to rectify the background noise and loss of low-level details caused by contaminants on the signal ground, you need to elicit the help of an artificial ground. An artificial ground is a sink of impedance lower than the house earth ground, so that high-frequency noise on the signal ground will drain away, leaving a clean reference behind.
Signal ground can be addressed two ways. The first option is to use an extremely low-impedance cable to connect the signal ground access point on the termination to the ground pin of an unused wall socket. However, the second option is far more versatile – a passive grounding box. Nordost’s answers to artificial ground are their QKORE Ground Units, a series of parallel grounding devices which can either separately provide an artificial “clean” earth for the primary side of the power supply (earth ground) with the QKORE1, and the secondary side (signal ground) with the QKORE3, or can address both the signal and earth ground together with the QKORE6!
For more information about grounding your audio system, download The Importance of Electrical Grounding in Audio Systems.