I chuckle sometimes that we are so obsessive about cable length. I agree that the longer run should be XLR whenever possible. If it makes you uncomfortable to have a 20 foot run of XLR between your preamp and amp, note that in live venues they run hundreds of feet of this cable, sometimes all the way to a recording van outside. Even in studios there can be 100+ foot runs of XLR. I have never seen one of the master recording engineers express a concern about XLR cable length.
Long interconnect or speaker cable
My room configuration requires that my rack is off to the side of my speakers. This means I need to run 20 feet of speaker cable (Wireworld) from my Mc mono blocks. This makes high end speaker cable cost prohibitive.
I was thinking I could move the amps next to the speakers, have short higher quality speaker cables, and then a long run of moderately priced XLR interconnects from my preamp.
So, all things being equal, what’s better for SQ, a long run of lesser XLRs or speaker cables?