Earth Lift Resistor

I have a tri- amped system. Hum, though low, has been a problem. I have almost eliminated it entirely through the use of earth lift resistors.

However, recently I have been advised that this is not safe. I would be grateful for the comments on the following:

Q1. Is it safe to put a series resistor on the mains earth?

Q2. Is 100R any safer than any other value?

Q.3 Is a WW safer than any other type? Is 3W WW the best rating?

Q4. Is there a safer way to fit an earth lift resistor to the mains?

Q.5 Is it more dangerous because I have these in many components in the system, not just the amps?

Q.6 Can the chassis go 'live' with earth lift resistors?

Thanks in advance.
If you are worried plug your system into a ground fault interrupter outlet. A GFI outlet detects if the current in the return wire is different from current in the hot wire. If so, power is going to ground through an unintended path (like your arm) and the power is switched off just like a circuit breaker.
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