Best Way for my TT to reach my Pre-Amp!?

If you're so concerned about capacitance of your long cables then you'd better buy an MI cartridge that is NOT SENSITIVE to capacitance at all ! 

This cartridge is Grado (for example). My Signature XTZ continue to impress me every day even against some expensive LOMC. 

All,

The TT is turned OFF for the following troubleshooting. 
I play the system fine on every other input. As soon as I turn the input on the Marantz to Phono, there is hum. 
How can this be? 

Pick up the marantz and place it one foot 12 inches in all directions. 
use a temporary stand if you have to. 
Does the Hum change ? 

You need a very well shielded phono rca cable from your tt to your phono input. There must be a third line just for ground (wire). As i said it's a bad idea to use unbalanced phono cable for longer than 1,5 meters (even this is too much). What is your cartridge? 

You can try external phono stage with short cable from tt to this stage and longer cable from phono stage to your line input. 

Ok I think we are onto something.

First, the noise didn’t change when I moved the Marantz around. Second, I have a second Marantz (same one) that I tried and the noise was exactly the same.

Third, even though the TT was turned off I decided to remove the phono cables extensions and it got rid of the hum. I’m assuming it got rid of the ground hum since there is no ground wire coming from a Rega table to connect. 
HOWEVER, even though the hum is gone, in the phono selection of my Marantz when I crank it up there is a smooth hiss like the ocean. Is this inherent in all phono or will an external preamp that is of higher quality get rid of this?

Finally, the rumble problem is still there but that’s different issue. 
Also,I don’t have an external phono preamp to try at the moment. I will be ordering one soon though.