Do no harm to a signal! Does this mean.....

Your premise isn't wrong, it's incomplete.

For example, if an inferior system is too bright, a cable can affect the tonality and, sometimes, improve it. That's not the ideal way to get good sound, but that's a way in which the cable adds something that improves the signal. It's like a mediocre spaghetti sauce; adding parmesan can't save it, but it makes it better, overall.

For example, if an inferior system is too bright, a cable can affect the tonality and, sometimes, improve it

Which justifies spending $2/foot not 0.50 for bulk wire.

Really. 

Yes really.

You want an IC to roll off the highs, you increase capacitance by putting the conductors closer together. You want speaker cables to roll off the highs, you increase inductance by spacing out the conductors. There is no magic.  However, doing either is highly system dependent, and almost always if you take your eyes out of the equation, not audible.


Some like Transparent add some cheap passive components to the cable. Some claim that adding a bias reduces noise (though the opposite happens). Some make claims about ground blocks, but can't seem to prove it.

Does anyone understand what happens to an analogue signal when it flows thru a speaker cable??

and challenges in transmitting a delicate analogue signal???

substance please