solved : my zs10 pro is plastic, spring1 is metal, when i put a plastic wrap around spring1 to prevent electrical conduction from metal shell to my ear skin, the buzz is no longer here. did bqeyz forgot to spray an electric insulating paint over the metal shell or is my spring1 defective and i must return it ? can someone with spring1 plug it in a source such as smartphone, dap or bluetooth receiver while source is charging via usb charger plugged in the ac wall and check for the 50hz hum ?, it should stop when source is unplugged from ac. ( i tried with bluetooth receiver, sony xperia xz premium, iphone se). buzz is stronger when you feet touches the floor without shoes on(insulation from soles reducing buzz intensity) and rememeber that if you hold source touching the metal chassis there is no buzz (for example put the iphone on your desk ). thanksmy laptop charger or phone charger are plugged directly into the wall socket, the difference i get is if i am barefoot on the floor (wood) or i wear shoes (lower level of hum due to soles insulation i guess). why are some iem not sensitive to this hum problem (like my zs10 pro) ?
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