Or, looking it from another practical budget perspective, if I have a total of of $1,000 to spend is it clear that I should spend $500 on each XLR pair, or should I “overweight” my spend on one set because it’s the more “important” interconnect from a sound quality perspective.
I think what is clear in one person's system is not so clear in another. Here's another curveball- suppose the suggestion above is correct and the phono to the pre amp has more of an effect than the pre to the amp: would it be better to entirely "overweight" the spending by adding just a $1000 XLR from phono to pre, instead of 2 XLR's in both places?
I would lean towards the former, because eventually you will probably have the itch to upgrade the $500 XLR's, but if you have one $1000 XLR you would just need to upgrade one, and you would probably get a bigger "wow factor" by hearing what the $1000 XLR can do, compared to $500 ones.
Providing of course you don't have a "throw away stock" XLR, and at least a Mogami or equivalent for the pre to amp XLR.