Isolated Ground causes ground hum.

What do you mean "isolated ground?"

@dangcaonguyen

By law, you MUST bond them to the house ground.  You can't just create a new ground field, and run a copper wire to your outlets and call it ground.

Best,
E

OK, so yes, you just created your own ground loop. :)

What you can do: 

Add more ground rods.
Bond them to house ground rod farmRun 1 ground wire directly to the ground rods, and use that for your outlets.

Then run phono grounds like normal, from device to device.

@JEA48

As far as I know, the NEC does not specificity a maximum number of ground rods, so long as they are all bonded together. That's what I am referring to.

Best,
E