NEVER remove the ground pin. Use an adapter if you must
lift a ground. It is best to check first if the ground pin is connected to any of the signal leads. If it's chassis only, removing it will have no effect.
Is it hum or ground loop? They are not the same thing.
Hum will usually be a purer tone than a ground loop which often contains buzzy noise components. Triac dimmers are notoriously noisy and phono cartridges make excellent pickups.
Have you checked the ground integrity. Many buildings have essentially no ground. It can be due to poor design, corroded connections and silly electrical code like allowing bonding to rebar in a foundation aka UFER
. My HiFi is connected to a copper rod that goes 10 feet into the ground. It has a dedicated circuit.
How is the gear arranged? Please list components and positions. Sometimes just re-arranging power cords or component position will solve the problem. Power cords should never be coiled or bundled with audio leads. Power cords should only be as long as necessary and cross audio lines at right angles.
Sometimes gear has a resistor between earth and its zero volts. Sometimes adding a ground lead from the offending gear to the next can solve the problem.
Be sure everything is off when changing connections.
Noise elimination is a step by step process. Start with the power amp alone and shorted inputs. At the absolute worst, there should only be a slight hiss with ear right next to drivers. If there is any hum, there could be something amiss with the amp or more likely the wiring. Add each preceding component with it's inputs shorted. Noise should remain nearly constant. If it increases, there is a system / wiring fault which must be corrected.
Assuming everything up to turntable passes, use shorting plugs on the phono input. If the noise is gone, the problem is the turntable / cartridge. If not, disconnect the phono AUDIO and apply shorting plugs
If the turntable is the problem, reconnect audio and disconnect the cartridge. Short the cartridge leads. If the noise is gone, there is a problem with the cartridge / phono input. Is the type / impedance correct?
If you must connect CATV - why?- to a HiFi, use a balun to isolate it, if necessary.
Using optical connections wherever possible on digital audio will preclude any possibility of ground issues.