I think for an issolated ground to really make a difference, the component that creates the noise (most likely a digital component like a CD player and DAC) should be issolated from the other components. If they are all on the one ground, whether issolated or not from the rest of the house, they will pick up the noise from the dirty digital or other component.
Using ungrounded outlets (or removing/floating the ground on the power cord) for your non-digital components will accomplish the same thing, as long as that does not create other problems. If the component only has a two prong plug, you are already clear.
Using ungrounded outlets (or removing/floating the ground on the power cord) for your non-digital components will accomplish the same thing, as long as that does not create other problems. If the component only has a two prong plug, you are already clear.