serial digital cable, RG-6, say from signature wire.
I use nothing else even for short runs, custom terminate and bam, no loss.
Termination along with source is everything. Many potential weak links in the chain.
75' plus and up, all my displays are remote from the equip.
Key phrase....point of diminishing returns not present.
Stranded wire works better over distance than solid core for IR, but your length should be no problem with Cat-5.