Kimber Hero I/C's and 8TC on C4's

Hello everyone

I have been upgrading my system for some time now but have kept my Kimber Hero interconnects and 8TC speaker wire throughout the process. Although I’m sure there are some gains to be had from much more expensive cables, I’m not sure how much of a gain there would be as I thought these cables and I/C's were reasonably good all-rounders. Am I doing myself an injustice by continuing to use these cables on my Dynaudio C4's with Plinius SA-103 and Tautoro or is it really time to step up. I do not have access to try different cables before I buy so any advice would be greatly appreciated.