RCA to RCA versus RCA to XLR

no benefit

This is an older HH Scott Tuner? Stick with the RCAs, be prepared for ground loop noise too. A lot of those were 110 vac.. Get a ground loop eliminator. That will fix you right up.. Doesn’t matter if you use a balanced input or not. The RCA is not.. it’s single ended just use RCA to RCA. The noise eliminator may work better on one end or the other too.  You may have to ground the the little gadget, they have that option..

Regards

Without seeing the preamp schematic I can't say for sure but it is likely you'd get an improvement in ground noise rejection as long as ground is connected to only the cold wire (XLR pin 3) at the RCA end. This may come at the cost of increased thermal noise, again depending on the input architecture of the amp. If you have no issues with ground noise then you may be best sticking with unbalanced.

Without seeing the preamp schematic I can’t say for sure but it is likely you’d get an improvement in ground noise rejection as long as ground is connected to only the cold wire (XLR pin 3) at the RCA end.

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I try to explain thing simply.

The Tuner has RCAs only, going TO a pre amp with both, RCA (single ended) and XLR (a few variance). There would be ZERO benefit for the Tuner and the pre amp supposedly has a lower floor noise because of onboard XLR tech, anyways.

Now going from the pre amps XLRs to another piece of gear with XLR plugs, should have a benefit. Though they are not ALL wired the same much less balanced just because they use an XLR plug.

BUT the source, this OP has, will see NO improvement other than enjoying a better type of termination. XLRs, if they were used, you loose the ability to move a ground loop eliminator on either end of the run..
I think that is a better reason to have RCA to RCA on both ends..

If you really want to help with noise (RFI EFI or getting high :-)) use a weave it is one of the best noise eliminator via no shielding.
RCA benefits big time from using JUST a weave..

Regards

I try to explain thing simply.

Thanks for the simple explanation, I'll try to explain as simply as I can why you are not correct. If you connect ground to pin 3 then it will be inverted at the input and there will be some benefit of the balanced common mode rejection (summing of inverted interference with signal interference). In addition to this the ground signal will see the input impedance which will vastly reduce the amount of current flowing through it... current flowing through ground is the definition of a ground loop.