Hum coming from Turntable

Thank you all for the awesome advise, it helps alot.  I want to ask if the body of all cartridges has to be grounded or certain cartridges doesn’t need the body to be grounded to the head- shell?  Also, can i say that all turntable tonearm & base has to have ground loop with the turntable body?   What happen if just the turntable by itself has a ground loop but the tonearm doesn’t or vice vera?   Will this cause hum noise?  

I would run all grounds to the same point.
If the cartridge is plastic or wood, then I am not sure how grounded they are??

If it is inducted field, rather than a ground loop, then it can get more complicated… but moving the switching supplies to another power strip might provide a data point?

Try this. Gently move your cart wires a bit with your finger when everything is turned on and the tone arm is “home”. See if that changes anything. I had ground issues for quite awhile and found that I had to have anything the turntable was connected to plugged into a single outlet via a power block of some sort. I currently use a Shunyata hydra which is great. Overall though, the ground issues I had related to the phono stage and it’s position relative to the tone arm. 

What happens when you disconnect the cartridge at the cartridge, first with clips isolated then with both channels shorted to their ground leads?

Try different cartridges to see if they are all affected similarly. Try grounding yourself and moving your cupped hand around the cartridge.
If the hum changes the cartridge is not well shielded.

The tonearm ground should be connected to the turntable which in turn should be connected to the phono stage. You can try floating the ground on your preamp with a cheater. I have an IEC power cord that has had the ground plug pulled off the male end I use for such occasions.