[size=10.0pt]As far as I am concerned, parasitic charges would be discharged simply touching the pro-bias plug.[/size]
[size=10.0pt]So, although not related with the issue you are experiencing, can you (gu sensei and hentai) describe, just for the records, how your power supply is earthed?[/size]
[size=10.0pt]I mean, do your wall sockets - also known as power points, power sockets, electric receptacles, plug sockets, electrical outlets or just sockets - have phase, neutral and a third pin for earth?[/size]
[size=10.0pt]It seems the third pin is called ground (earth-earth) and the second pin is called neutral (earth-neutral).[/size]
[size=10.0pt]I am not an expert, so read this with a grain of salt (cum grano salis). Usually the earth net is isolated from the neutral (return) net, although both go to earth anyway. But there are some installations in which neutral and ground are combined. [/size]
[size=10.0pt]It seems that both arrangements have pros and cons. [/size]
[size=10.0pt]With isolated nets for ground and neutral, there would be still stray voltages (I guess these tiny voltages do not affect your amplifier). [/size]
[size=10.0pt]Connecting the neutral to the equipment case provides some protection against faults/shorts, but may produce a dangerous voltage on the case if the neutral connection is broken (in this case, it is better to have a separate ground).[/size]
[size=10.0pt]Eventually an electrical or electronic will shed of light on this subject.[/size]
[size=10.0pt]It would be nice to know if you both are using plug adapters to cut any earth loops (i.e. your source is already connected to earth with the third pin and your XLR cable has shield soldered at both ends so that you had to let the third pin on the amplifier floating).[/size]
[size=10.0pt]I am not sure if such issue is related to these questions. As I said, it is just for the records.[/size]