Best way to handle this ground loop

A current of 50mA (barely enough to make a low wattage lamp even glow) is sufficient to send your heart into a state called ’ventricular fibrillation’, where the heart muscles are all working out of synchronisation with each other. Little or no blood is pumped, and you will die within about 3 minutes unless help is immediately at hand.

https://sound-au.com/earthing.htm

If ground pin is disconnected, for safety reason please at least use a GFCI adapter.
The GFCI will “sense” the difference in the amount of electricity flowing into the circuit to that flowing out, even in amounts of current as small as 4 or 5 milliamps. The GFCI reacts quickly (less than one-tenth of a second) to trip or shut off the circuit.

https://images-na.ssl-images-amazon.com/images/I/41PoSuePdNL._AC_.jpg

"...No, there are no RCA without ground..."


I use a product similar to this in my hum busting kit. They help isolate the problem. 

https://www.conferenceroomav.com/p/hall-research-gli-rca?gclid=EAIaIQobChMImJvSo4zk7QIVkxx9Ch2H4Q3AE...

sjeesjie

... the splitsecond there’s current leaking to ground, a fuse will be blown.

Perhaps. But you do not want your body to be part of that electrical path.
FYI: It's called a "safety ground" for a reason.

Although hififan's link describes the different ways a ground fault can occur, he never states that there is a difference in ground potential; a different impedance between the earth grounds.

Never lift the ground.  Find the component that is causing the ground loop and either get it repaired (bad design) or replace it with something that actually is designed correctly.

It is quite simple to find out which component is causing the ground loop.

Connect only the amp to the speakers and turn the amp on.  Noise?  yes, it is either the speaker wires or the amp.  No noise?  then connect the pre-amp to the amp/speaker combination without inputs to the pre-amp.
Noise?  yes? then it is either the pre-amp or the interconnect wires from the pre-amp to the amp.
Connect a source to the pre-amp with interconnects.  Turn equipment on.  Noise?  yes/no?  you see where I'm going with this?

poorly designed electrical equipment that have poorly designed grounding system are rare non-a-days, because designers have learned over the years.  However, you might run into something that just has a bad ground design.  Or, interconnect cables that are poorly designed. 
Under no circumstance do you lift the ground on a piece of equipment.  The ground is there for a very important reason and in the event of a fault, current will seek the easiest path to ground and you, your family, pets, etc. may become that path.  
anyone telling you to lift the ground does not know what they are talking about.  Find the faulty equipment and either fix it or replace it.  

be safe and enjoy