a great take on big$ cables

Pabelson:

you have to invent and carry out some sort of blind test

You got it... A long term test...

How do you know you're not imagining a difference

You can measure differences (how about 0.25% difference?) in THD between the two and still won't be able to tell the difference in a conventional DBT with one minute clips. What do you think?!

The answer is, you don't know, and you can't know unless you compare them blind

So, when (not if!) you fail the above test you will sell your main gear and listen to a boombox for the rest of your life, just because you arbitrarily decided that "you can't know unless you compare them blind"? The emphasis is on arbitrary, until I see a conclusive research that shows consistent statistical correlation of DBT to sonic perception.
Without that, you are making an arbitrary decision that the particular method is a good indicator. I'm looking for the science here.
Go back and look at the roots of scientific evaluation. Even Einstein's theory of relativity had to wait many years for "official" proof, until someone could measure the effects of gravity on light. We tend to simplify and take things for granted, but that is not scientific. What's scientific is for one to ask why isn't reality in agreement with Newtonian mechanics and dare say that the speed of light is constant, risking ridicule by his colleagues.
You can ignore what your brain tells you based on what seems to be an incomplete or insufficient test data. That is not science, even though it includes scientific methods. I'm sorry that I don't know the answer, but I do know what to ask. You don't!
You seem to accept it that someone with X years in the audio industry "gotta know" more than what your own ears tell you. With that approach we wouldn't have an atom (which nobody could see at the turn of the twentieth century!) and would be still teaching Greek geometry instead of Calculus in our schools (Newton was "blamed" to be insane with his definition of infinitesimals...)
Dare to question!

Differences in copper or silver should be relatively small, as Mr. Russell's website shows. Their sonic impact should be subtle.

But my ears tell me that with many cables there is an immediate and not very subtle impact on the sound (I don't need any double blind testing to hear this). To me, that means that these cables are not just wires, they are designed to have a sonic impact. Cable designers want to achieve a certain effect (ie, "silky smooth" or "natural-sounding bass"), and combine materials with cable geometries and passive circuit elements to get that effect. In other words, the cables are designed to be filters to produce certain effects.

For myself, I want to spend the money on the active circuits. If a cable changes the sound, I don't want it. I use what other people may think are crap cables, but you know what? They don't have any sound at all, they let me hear the amp and preamp and speakers, and most importantly the music.

Someone should make a little $100 box that implements a tunable band-pass filter to put in the interconnect lines. I bet that you could make such a box with some knobs that would let you make your interconnect sound like "silver" or "copper" or "quantum equalized equipotential polarized dialectric" cables. Zip cord plus a box like this would be as good as any $15000 cable.

On the other hand, I plan to audition Transparent cables on the advice of a friend. Through their extensive R&D, they may have found ways to make my system better, and that's worth listening to.

Where to begin, Serus? Just because you don't know the science doesn't mean the science doesn't exist. The study of human hearing is over 150 years old. Audio is not some brand new, revolutionary theory that requires confirmatory tests no one's imagined yet. Audio is old hat, much of it borrowed from other fields. And the way human hearing works doesn't change based on the faceplate of the gear you're listening to.

One thing that science definitely does know is that "what your ears tell you" can be wrong. If you can't accept that, then there is no reasoning with you. Believe what you want to believe.

The study of human hearing is over 150 years old

Well then, inside the scope of human--and planetary--history, this gnat's fart of a research period ought to be enough cause to question our young-punk conclusions. We are mere infants when it comes to understanding our own functioning. So enjoy the music, or not.

Someone should make a little $100 box that implements a tunable band-pass filter to put in the interconnect lines. I bet that you could make such a box with some knobs that would let you make your interconnect sound like "silver" or "copper" or "quantum equalized equipotential polarized dialectric" cables. Zip cord plus a box like this would be as good as any $15000 cable.

That's the Carver "theory" applied to cables... And it is not true. A "box" with passive or active components does not behave the same as a transmission line in regard to RF handling or even in regard to the full audio spectrum. You are making a big simplification of what should be analyzed by Maxwell equations and perhaps simplified to distributed network. The "box" theory says that it all can be simplified into an "ideal" transmission line plus ideal basic components. That's known in engineering as the first-order approximation. It's good for predicting basic directions, not for details.
BTW, you can simplify the concept even further by putting an equalizer in the chain. If all these transfer functions are linear then you can "bundle" them together!
Some online magazine measured and published Nordost Valhalla capacitance curve. No passive components that I can think about can do that...
Equalizers do some good in some systems but they are not "sonically-free", whether active or passive. If you bother to reach the highest levels of audio reproduction then you will take the extreme pain to match the most basic components and avoid additions to the signal chain.

On the other hand, I plan to audition Transparent cables on the advice of a friend. Through their extensive R&D, they may have found ways to make my system better, and that's worth listening to.

Ah, and then your emotions take over... It won't make a difference, but heck let's have a listen... :-)
Be strong and resist the urge, Mate... :-)
Or, listen and think whether this set of cables seems to do a better job conveying the music compared to what you have. I'm not saying the particular one does or doesn't, but only listening in your own system can tell you the whole story.
Of course if you know the "formula" of this cable or the circuit for that amplifier - you can build them yourself. The question is how much is it worth to you... To some people an interconnect is worth $50 max and even when they hear a better set they won't spend the money. To other people money is no object. Most of us fall somewhere in between... See - we were just reduced to an "average"... :-)
But somtimes, just sometimes, the emotions take over. Like my friend that needed to rebuild his garage and one day I go to visit and he has a $40K dCS digital front-end - and no garage... The mysteries of the mind... :-(