I agree that the suggestions by Rives are good. The isolation transformer may be a tad expensive though.
If you do not use a transformer, the only way to get a true Isolated(in contrast to Dedicated ground)ground, is to have the electrician put an isolated ground bar in your new sub-panel, and run a separate ground wire that is not grounded to any thing else until it reaches your main house grounding point, where it will need to be connected per the National Electrical Code.
Then your electrician can install true isolated and dedicated grounds to each Isolated ground type receptacle you install. This will ensure a separate grounding path back to your main gounding point with no other grounds tied to it in-between to create noise.
If you do not use a transformer, the only way to get a true Isolated(in contrast to Dedicated ground)ground, is to have the electrician put an isolated ground bar in your new sub-panel, and run a separate ground wire that is not grounded to any thing else until it reaches your main house grounding point, where it will need to be connected per the National Electrical Code.
Then your electrician can install true isolated and dedicated grounds to each Isolated ground type receptacle you install. This will ensure a separate grounding path back to your main gounding point with no other grounds tied to it in-between to create noise.