Grounding, is it possible to do without it?

Question

Electronics

In general, the monitor speakers Presonus E4.5 are phony, and if nothing is connected except the power supply. From any outlet in the apartment. There is no grounding (and will not be).
Is it possible to somehow eliminate this effect? Creative's soundcard had a Ground Lift switch to remove these effects.
I can try to disassemble the monitors and break the circuit between the case and the amplifier ... but I'm not sure if this will solve the problem and that everything inside is so simple.

Can this problem be solved with a double conversion UPS? (On-line) The UPS will also be without ground.

Smart people on the Internet say that instead of earth 0, you can make contact, but something tells me that this is a rather controversial solution to the problem.

The last option is to do the grounding yourself (throw a wire from the fifth floor, hammer asphalt and lay down electrolytic grounding) and it will probably cost more than 100k rubles. There is still a transformer substation nearby, but where is its grounding and whether it is possible to ground there is also a difficult question.

Answer 1

Any speakers will phon if nothing is connected except for power. The input of the op-amp is not connected to ground, an empty wire dangles - which works like an antenna, catching all available interference.
This is fine.

Answer 2

Try to carry out two tests:
1) Plug the plug into the socket in two ways
2) If it does not help, short-circuit the input (the signal plugs of the tulips on the balanced input flange).
and post the results.

Answer 3

If the electronics in the speakers themselves are shit, then nothing can fix it - just replace it.

Answer 4

disassemble and look at electrolytes, barrels of capacitors, possibly swollen by nutrition