For people just starting out in this hobby (as are most people on this site), it's not surprising that differences can't be heard.
Starting to hear real differences between headphones is equivalent to being a 1st grader learning how to add and subtract in mathematics. At that stage of auiophile/hearing/brain development and training, trying to hear cable differences is like jumping straight to trigonometry.
Or, if you like, it's like learning a new language. You start out with "see spot run" and you master that. But that doesn't make you qualified/prepared to turn around start reading Proust in the original French.
Of course it doesn't make any sense. Over time and experience, your ability to discern these things develops like a muscle.
You may just not be ready yet, Grasshopper.