I was skeptical of pc impacts until I did a blind comparison with a group of both hobbyists and casual listeners. Was comparing stock pc's to midrange Nordost (Frey 2, Heim 2) cables on Luxman M900U monos, Luxman C900U pre and Esoteric N-01XD streamer/DAC.
Even the casual listeners noted better "clarity", especially with vocals and individual instruments, with the upgraded pc's. I was frankly surprised by the repeatability of the results. For my system the priority for improvement was pretty clearly the monos first, streamer and then pre.
As noted, my comparison was to the stock pc's, I still question the "linearity" claims by many of the cable makers but there is no doubt for my system that cables can have an impact.
Ultimately you need to do a comparison in your system to determine if the upgrade cost is justified for you. One suggestion I would add, however, is to do the comparison with cables that represent a major step above your current cords. Doesn't mean you have to go with those but will help you determine if pc's make a real difference.
Good luck...