I have no clear notion of what is going on, but I just wanted to point out that a static discharge can be very very high in voltage (thousands of volts or more, over the span of a few micro- or milliseconds), although vanishingly low in current. Therefore, I could imagine that such a discharge would pass right through a volume control, regardless of its setting.
Also, before one feels confident of having eliminated a static charge with fancy external gadgets, one ought to look at the following: Are you wearing leather soled shoes? Does the turntable sit over a wool carpet or the like? Is your body grounded? Very often the cause of static charge build-up is "us".
Also, before one feels confident of having eliminated a static charge with fancy external gadgets, one ought to look at the following: Are you wearing leather soled shoes? Does the turntable sit over a wool carpet or the like? Is your body grounded? Very often the cause of static charge build-up is "us".