better grounding, or cleaner grounds can fix a lot of the impression of 'grunge' in some digital based audio systems. Not always, but it can happen.
same for purely analog systems. the ground and it's qualities can be and is important. This can be a problem in apartments, high rises, places with bad grounding dry grounds around the house in situ, or dried out oxidized ground rods, etc.
I tend to encourage show runners (the people putting on audio shows) at hotels, in hotel rooms, to hire an electrician and to go around and check all the connections in all the panels in the rooms, to re-screw all wire connections (loosen and re-tighten), to flip all the breakers, etc. This will generally make the entire show sound just a hair better, and makes some rooms go from disasters to OK.