Again I will say that if you add something new to your stereo and concentrate really hard, you very probably will hear a difference during an A/B test. Perhaps even an improvement. If you leave the house for a few hours or perhaps even a weekend, would you notice the cable change? In most cases, I would guess no.
All this being said, I have heard the difference in sound between cables, but I doubt that I would notice a change in interconnect and speaker cables from my mid-tier Audiquest to high-tier anything, if I were to take a weekend vacation and come back to my stereo. It's not just a blind test I'm talking about. You must add duration. I think that is fair because there is always a duration between one listening session and another.
Now, let's say that I could hear the difference after a duration if I put the most expensive cables on my stereo. I'm guessing that even used, trading my cables in, it would be well over $10,000. Would the difference in very expensive cables be worth it? Say, if I took that money and bought a new amp instead.
Audiophile trade-offs. How fun.

