I have been involved in wiring audio and video editing suites in the past, both power and signal wiring.
For minimum hum and noise, a "balanced" power configuration was used. Critical equipment branch circuits (those feeding equipment racks, mainly) were fed from a special isolation transformer with a center tapped secondary, with the center tap grounded. Voltage from "hot" to "neutral" blades of receptacles is 120 V, but hot or neutral to earth ground is 60 V. All circuits were isolated ground, as well. RF noise filter installed on the power entrance to each rack.
All racks and cabinets bonded together with 2" wide copper strap, running back to the distribution panel, and on to the main service ground.
All power wiring in EMT for RFI shielding, with care taken to avoid parallel runs of power and signal wiring.
