Do speaker cables need a burn in period?

They may not be outlandish. They may be just right in Neverland or any other fantasy land. For normal living people, they are a sad joke. Relax your room, you will feel better. So will your cable. Nervous rooms and traumatized cables are a big problem in Hi-Fi.

It is not all I got. I use your references so you can easily find it yourself, too.

On these 18 pages, and between both camps, you could not collect 100 sentences that would qualify as somewhat scientific. Most of the "scientific" attempts are good for shrugging shoulders and not much else. There are lots of testimonies, but they are on both sides. Nobody wins.

I follow this thread because I do not have an opinion if burn-in exists or not. However, some of the claims and theories presented are not making a strong case for it. For now, the opponents are a bit more eloquent in refuting it theoretically.

For now, the opponents are a bit more eloquent in refuting it theoretically.

Eloquent is not the enemy of truth at all. It is just nicer and more coherent way of expressing it. Think of it as "truth with a style" rather than "truth with whining".

Whatever the truth about burn-in ends up being, it is, except for manufacturers, only of academic importance.

I am not sure where did Marx land from in all of this. He lived way before speakers and amplifiers, I think.