Grounding facility has always been there for the sole purpose of safety.
For example, shock hazard prevention, lightning protection, noise shielding and other functions. In an audio setup, the effectiveness of the grounding facility has an immediate impact on the background noise.This translates to poor sound quality and greatly worsens the listening experience.
It is almost impossible to get satisfactory grounding facility, let alone one that meets the requirements for audio use. Most of the time, they only adhere to the minimum safety requirements. The common ones have the Neutral wire and the Ground wire connected together, or there is no Ground on the receptacles, leaving the Ground wire unconnected. This allows noise from the home appliances to pollute the Neutral wire, hence, causing interference.
Electrical appliances like inverter air conditioner and those with switching power supplies, like computer, generate the highest level of interference. When the electrical reference point is polluted with noise, it could get into the signal path and you could hear it as noise. The noise could potentially enter the digital circuit and cause bit error.