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

Let me start out by thanking the OP for starting this thread. I’m a relative noob to all this and will be adding a phono stage to a receiver(Oulaw RR2160) as well. Which I think would be the best solution for you if you just don’t lengthen the cables. I’m learning quite a bit from this thread. For the record I’m looking into mostly tube phono stages and will most likely move into a integrated amp a year from now.

For the money, it’s hard to beat the Schiit Mani and Blue Jeans LC-1 low capacitance RCA cables, and will far exceed the built-in phono stage of your receiver. Been there, doing that.

My thoughts right now is just go with a pair of extension RCA cables and see what you think.
I'm betting you will be quite happy.
I had a TT sitting in a similar fashion, it's cable was 18" too short to reach.
I made it work even more down and dirty with a pair of RCA adapter and another regular set of RCA cables.
Sounded PDG to my ears.
Of course that was just temporary and I had a longer phono cable made from the TT to reach.
But my point is before you blow a load of dough just try it.

Greg is correct in that the Marantz is going to be the limiting factor no matter how good an independent Phonostage you put between it and your TT.

Don’t forget you’ll need to ground your TT.   Phono pre will likely have a place to attach the ground wire from your table and so is a good solution to that aspect.