TT Hum

Almost any cartridge will produce a faint noise if it is in space, not touching the LP surface, and if you then turn up the gain high enough. That is more a function of the phono stage signal to noise ratio and/or ambient electrical noise, than it is a function of the cartridge.  But on the one hand you do say it only happens when the arm is resting, which fits my theory.  Then you imply you hear the faint noise on your digitized copies of LPs, where the stylus must have been tracing a groove, which contradicts my theory.  Which is it?  The cartridge hanging in space is like an antenna which picks up stuff and then delivers it to your phono stage, which has a lot of inherent gain.

Mijo, I ask this out of curiosity, because you raise an interesting question: how many cartridge bodies are grounded or even can be grounded, unless there is continuity between the cartridge body and one of the  audio grounds available at the pins?  As you know, many cartridges are made of plastic or other non-conductive materials.  Also, many headshells are non-conductive (made of wood or carbon fiber, for example), so grounding through the headshell is often not feasible.  For that matter, the only cartridges that would be shielded would be those with conductive metal bodies that are then grounded preferably to the chassis.  I am not implying that your advice is not good.  I am just curious whether I am missing the point.  Thanks.
This is not at all to say that you are not correct in guessing that the OP's cartridge is picking up some radiation from the electronic panel under the tonearm.