XXHighEnd

Some bits of Hi Fi kit, once plugged in the mains, have a tiny vibration/hum in the casing. It's not transformers vibrating but it almost seems as if the casing is 'alive' particularly when touched very softly with the hand.

I'm sure its not a safety issue as this occurs on new kit.

What's occurring here and is there an impact on sound quality?

Chris,

What you feel there is current. Or maybe I could say : the "charge" the chassis received.
Not good for SQ at all.

Unplug all your interlinks and other inter-device connections, have them powered on, and measure the voltage between the various chassis'.

Try to have the voltage (the potential difference) to be the least in all situations.
Most often this is a case of twisting the plug 180 degrees - something we can do over here. You can do it too, but you must make your own plugs and sockets.
Otherwise try all the combinations with - and without mains earth. Again something you can't do easily but this time it needs a modded (extension) socket only. Have a larger one, and cut the mains earth from half od the sockets. Now you can play around.

Regards and have fun (ahum),
Peter

Thanks Peter, when you say twisting the plug 180 deg do you mean (for us in the UK) swapping live and neutral?

Sound like a good job for a wet afternoon.  ;)

Yep Chris. And I now realize that our 180 degrees is quite obvious with two opposite pins. Not so with an uneven triangle ...

haha

Peter