Blind testing is useful for a panel of jurists. It keeps everyone honest. If you only think you hear a difference then you likely don’t. Save your money. On the other hand if you find you can’t live without the new component then you have my sympathies. We’ve all been there.
For me buying cables is not much fun. The only thing worse is buying insurance. Cables just aren’t sexy like a good looking amp, or speaker. And worse of all is the uncertainty that I found the best possible combination/synergy for my system. Maybe the same goes for amplifiers and speakers but it just seems easier to decide on those components.