In my experience Power Cables and Digital Cables can make big differences while Interconnect and Speaker Cables make very small differences.
I'm always shocked at just how easily differences can be perceived between power and digital cables. I find decay reproduction and low-end performance can vary significantly from cable to cable.
On the other hand, I generally hear very little difference when comparing interconnects. I've tried many different RCA interconnects and always end up returning to my budget Wireworld cables because I never hear enough difference in interconnects to justify the cost.
I once took part in a blind speaker cable test. A set of very expensive speakers cables was compared to a pair of car battery jumper cables. There was no consensus in the room as to which one was preferred.