tomp wrote:
Walt is absolutely correct about running alternate grounds from a sub panel. That will cause the code people to have a fit. However, there is nothing to say that you can't run a separate ground from, for example, the ground on a turntable arm. As Walt says, you may cause more problems with ground loops depending on where the alternate grounds are in relation to the main service feed ground. Other than violating codes, there is no one solution for lowest noise. As I found when running a USB DAC off my laptop, the internal laptop noise filter shunted noise from the inside of the laptop to the power supply ground which then traveled down the house ground wires to the amplifier causing noise. There was enough impedance in the house ground wires to cause the grounded body of the input jacks on the amp to pick up the noise. Having a super ground somewhere near the service panel would have done no good because the noise occurred on the ground wiring itself in the house walls before it got to the ground point. Finding noise sources and correcting the problems is one of the most difficult things.
I can't begin to complain about the hum chasing I have done over these many years. Even with a relatively modern house with a sweet 10-foot ground rod tied to my service and water pipes. Luckily that was in the past -- I chased the hum and caught it.