I'm using a single 20 amp circuit that uses an isolated ground outlet (ugly orange) and 12-3 BX back to main panel. Grounded to main buss bar. Got great (no noise) results and pretty cost effective. Red wire wrapped in green tape to designate ground. Maybe Gbeard can comment as to whether BX or conduit is over kill compared to romex (will certainly increase cost) and add a simple definition of "Star Ground".
Some schools of thought recommend monoblock amps be connected on opposite sides of main (common noise cancellation). General consensus in non-monoblock situations is to keep all lines on same side of main. May also be some benefit to locating potentially noisy house lines (those with motors, dimmers, computers, etc) on the opposite side of the main. My computer for example has it's own 15A (14-3)iso grd circuit on opposite mains side.
If you still have noise issues after a code compliant install look for the source by switching off suspect items. Deal with not generating the noise rather than floating the ground and risk floating to heaven.
Some schools of thought recommend monoblock amps be connected on opposite sides of main (common noise cancellation). General consensus in non-monoblock situations is to keep all lines on same side of main. May also be some benefit to locating potentially noisy house lines (those with motors, dimmers, computers, etc) on the opposite side of the main. My computer for example has it's own 15A (14-3)iso grd circuit on opposite mains side.
If you still have noise issues after a code compliant install look for the source by switching off suspect items. Deal with not generating the noise rather than floating the ground and risk floating to heaven.