I've owned the Cardas Sennheiser cable. There was no difference. I left it on for a couple of years to make sure.
The standard reply is that there's something wrong with my hearing. I doubt it. I've spent a few thousand hours playing music and have very good relative pitch. I can tell when my instrument goes sharp or flat and can tune myself nicely compared to electronic tuners.
But the cables did nothing. My oscilloscope and DMM agreed.
Are you saying that you're completely immune to things like optical illusions? They get me every time. Seem to fool everyone else, as well. What you think you're hearing is the result of expectation and placebo. This is well-illustrated by numerous tests of wine. People taste what they expect to taste. Tell them that it is an expensive wine and they think they're tasting an expensive wine. This is a normal human reaction. You're not a bad person and there's nothing wrong with you. You're simply hearing what you expect to hear.
This is why cable "differences" vanish when a person doesn't know what cable they're listening to. Take away the expectation and the difference disappears. You'll probably launch into a complicated explanation of why the listening tests are "invalid," but the simple truth is that they negate expectation and placebo biases. Without those, cables all sound the same. This has been demonstrated time and time again.
And if your ears are so golden, please tell us about the channel imbalances in your gear. If you've ever worked with electronics, you'll know that there is a tolerance in every cap and resistor. Usually 10% or so, but the very best can be 1%. I strongly doubt your equipment is at 1% or better. That takes buying a quantity of each component and carefully matching them between channels. That's very expensive and I don't know of any manufacturer that precisely matches channels. Meaning that there is probably a 10% or so difference between the left and right channels in your gear.
Can you tell me which channel is stronger than the other in your rig?
Now, it'd be a simple matter to take a DMM and measure the difference between R1, etc. in your left and right channels. This could be done with a wide variety of test gear, all producing the same numbers. And there will be differences between channels in 20-40 components in your gear.
How can you hear unmeasurable differences in cables when you cannot hear the measurable differences between left and right? If your ears are that sensitive, then you should be hopping mad that your left and right channels don't sound precisely the same. It'd be quite easy to prove, without question, that your left and right channels have different output.
So which channel is stronger than the other in your amp?
I won't even begin to go there regarding the channel imbalance since whatever imbalance I do perceive might be due to slightly less sensitive hearing in one ear than the other or to the recording or to other factors such as the one you mention. You are so persuasive that I actually took my stock cable out and started using it to see if I noticed any difference. Maybe I was imagining it. Nope. Immediate perceptible difference. I will say you are the very first person who has actually listened to both cables and didn't hear a difference. Congratulations on that. I won't criticize your hearing. I'll just stick to the Cardas. It's no skin off anyone's back which cable I listen to.