I think the problem is that people always ask the wrong questions or ask them with the wrong potential answers in mind.
A better question would be can a difference in conductor materials make a difference audible to the ear? If you hear a difference is it because said conductor sound different or is it because their properties cause the circuit to behave in such a way that you hear a difference?
Now, in my own experience I can swap out electrolytic capacitors in a signal path for films, and I absolutely hear a difference. But is this because difference in dielectric makes an audible difference or because the way it makes the circuit behave makes a difference?
Personally, I dont care; I just appreciate the difference. I found long ago that experimenting on ones own is best because we all hear differently, and I wasn't making any progress listening to others tell me what I should not hear.
Same situation arose when people kept telling me that with my particular pair of headphones I should not need more than tens of milliwatts because of their efficiency, and yet the higher the power of the amp I ran them on, the better they sounded, and all their till-then trademark insufficiencies disappeared. Now, one could argue that it was simply due to a better designed amplifier, and not the wattage it could supply, but even if one accepted that as a given, it still resulted in better sound. So telling me not to pursue higher power was still bad advice because it still yielded a better experience.
As far as power cables making a difference, I'd say they mostly do not. But then you could have situations where the power was dirty enough that changing cables would never have shown a difference. My apartment runs entirely off a single 20A breaker, and it made a noticeable improvement when I put my listening rig on a large power conditioner. Maybe now, I should try different power cables. But I'd rather change things that absolutely make a large difference, such as crossover capacitors / resistors and bypass caps, etc.