I've got aftermarket preamps in both of my Ibanez basses. An Aguilar OBP-3 in one bass and a Nordstrand 3b in the other. The preamps have been installed for awhile and I don't really have any noise problems. But I was looking at diagrams and reading about how pot casings should generally be wired to ground. Neither bass is wired that way. They both have shielding paint in the control cavity. I just grabbed my mulit-meter, set it to continuity, placed one probe on the shielding paint, then touched the other probe individually to the backs of the pot casings. And I get continuity with every pot casing. In other words, it appears the pots are already grounded via their mounting hardware. In this situation is there any benefit or reason to ground the backs of the pot casings? Thanks!