I personally have three dedicated isolated ground 20-amp circuits for my system. Two 100W mono block power amps occupy one circuit each and the other 20-amp ckt is for pre-amp/xport/dac on a line conditioner (this has the advantage of allowing the amps to draw current almost without limitation and to isolate the harmonic currents generated by digital units). Each circuit is on a three-wire armored cable (BX) - hot, neutral and isolated ground. Each of the three ground wires is routed to the ground bus (NOT the nuetral) of the panelboard.
I live in New York City where 2-wire BX branch conductors are mandatory. The most annoying problem with these is that they act as an RF antenna since the metal jacket/outlet box is the grounding conductor. By using isolated ground receptacles, you physically separate the outlet from the electrical box. This also breaks the ground; and the third conductor becomes the legal ground. By routing the ground to the ground bar instead of the nuetral bus, you greatly reduce the effect of harmonic currents (noise).
If you chose to go with one circuit, the wiring is a little different. A two-wire circuit is run as normal to the isolated outlets - but you must run an individual ground from each receptacle back to the panel.
If you like, email me for a wiring diagram. This is something any competent (licensed) electrican should do without blinking an eye.
