> Vacuum-tube amplifiers are not in the same class with techniques that are unlikely to have any perceptible influence on what you hear.

Yes, they are. The Carver Silver 7 was built to demonstrate this. [1] It's a tube amplifier with 38 tubes per channel that costs $17,000. It has all the important features - weighs 68Kg, vibration damping mounts, takes four minutes to power up, and the wiring is silver. Gets good reviews from the High End crowd.

Then Carver built the Silver 7 T, a transistorized amp with the same transfer function. As a demo, the Silver 7 and the Silver 7 T can have their outputs differenced, or wired up to cancel and drive a silent speaker. Same output. Gets terrible reviews.

[1] https://hometechnologyreview.com/CARVER-SILVER-SEVEN-MONO-VA...

This is exactly what I have already said.

Typical transistor-based audio amplifiers are different enough from traditional vacuum-tube amplifiers, but when the cost does not matter it is possible to design transistor-based amplifiers that are equivalent with vacuum-tube amplifiers.

The example given by you shows that there are indeed many people who do not truly perceive the differences or non-differences, so they judge based on prejudices. Of course, I agree that there are many such people and the gold-plated cables were intended for them. I agree that they must exist also among the customers buying vacuum-tube amplifiers.