Switch audio output problems

I'm trying to output switch audio to powered speakers. The problem is an horrible ground noise if it is docked, or charging. After some research, I found that the noise is caused by the power supply (ground loop), that is not properly insulated. I tried another charger (undocked) and noise is reduced a lot, but no completely removed. This brings me to think that the switch' sound chipset isn't neither properly insulated.Do you guys have the same issue, and how you have resolved it? Do you recommend me some suitable charger with good insulation? Do you think that if I use a shielded audio cable will resolve it?

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Edit: Through HDMI output on monitor speakers, the noise is a bit less, but perceptible