[edit] about 10 posts too late
Cables are scams. If you want to argue the cable is non microphonic to the point it has zero mass and floats in the ambient air currents.. nice! If you want to argue it is unbreakable and will last 50 years... cool. If you want to argue you like wearing a blingy necklace consisting of an IEM cable... nice! Anything else is snake oil scam territory.
I think part of the problem is that the approach to the issue is somewhat backward, at least in terms of the title of this thread.
Beyond that, I think there's a lot of talking over one another, and the actual point is lost.
So, what is the actual point? What do we really want to know?
It seems to start as "Do cables make an audible difference?"
And then there's a second aspect which comes in that I think starts arguments: "Do cables make an audible difference to me?"
When we ask if cables make an audible difference, we must also answer the question, "How do we know if cables make an audible difference?"
That question is easily addressed: measure it. The technology is there, and it's more precise than human hearing.
This also allows us to know the answer to a related question: "How could cables make an audible difference?"
Again, this is an answerable question. The short version is that if the cable represents a change in resistance, inductance, or length (and your cable isn't long or short enough to do that), it may raise or lower the voltage it delivers to the transducer by comparison, changing the output volume only. Impedance also plays a role if the transducer has varying impedance across different frequencies AND the cable resistance (characteristic impedance?) is high.
However, high cable resistance (characteristic impedance?) is
categorically undesirable. Why? Because the output would vary depending the transducer. Imagine that you make sunscreen, but it doesn't provide the same UV protection to any two people. Some people would be fine, others burned and no way to tell who would burn or who would be fine ahead of time.
Worse still, unpredictable changes in certain frequencies by a transducer would significantly impair the ability for an end user to accurately reproduce the source sound. He or she would have to impedance match or EQ to get the desired end product. A cable manufacturer would have to be a colossal schmuk to make a cable that would have unpredictable results based what gear the end user had; there would not be happy customers. You wouldn't have a product that could reproduce the same result in almost any scenario.
All of the above consequences, by the way,
are measurable. We would know if they occurred, because we would see changes in the transducer frequency response. That we have someone measuring cables which shows no changes to the frequency response gives strong evidence that those cables do not make any changes to the sound characteristics.
Frankly, I'm not aware of any cable - that isn't f'd up (ie, defective) in some way - that produces a measurable difference.
But none of the above answers the question: "Do cables make an audible difference to me?"
As I wrote previously I had thought I had heard differences in cables,
when I wanted there to be a difference. I'm human, however, and that means I'm subject to cognitive biases, such as expectation bias as I just wrote, confirmation bias, the placebo effect, and more.
When someone isn't cognizant of these biases or how they skew our perceptions, I believe that's when we get someone who has verified to themselves that the answer is "yes" cables make a difference. This is where I think we get the Biff Tanners coming in and arguing because they are answering one question (rightly, I would say, because that's what they experienced), and aren't aware that others are discussing a completely different series of questions. Questions which have specific, measurable answers.
One question I have for those who do believe cables make an audible difference: how could a cable make an audible difference that isn't measurable in some way?
I've never seen a satisfactory answer to that one.
Night everyone and thanks for coming to my screed.