Speaker Cables

[B4ICU]

The theory is very straight forward: the cable is a pair of resistors (in fact more complex load as it is a combination of resistor and capacitors) that you put in series  in the circuit formed by the amp and the speakers.

The thicker the cable, the lower the resistance. Therefore if you consider that not to be heard the added resistance needs to be less than 1/10 of the output resistance of the amplifier (don’t take 1/10 as a real value it’s just for illustration purpose), you would ‘need’ a cable showing 100 less resistance for an Amp having a damping factor 100 greater.

Or if I take the example given by @B4ICU a Devialet would benefit from a cable 1000 times less resistive than a tube amplifier would.

My two cents

Jean-Marie

There’s very little resistance in a few metres of simple cooper cable so that’s impossible to achieve.

Hi

How little?
if you got to the AWG table: https://www.powerstream.com/Wire_Size.htm
you can see, that a #12 AWG cable of 10 ft. (3m) which is actually 6m as there are two wires connected in series: 
It's 5.2 Ohms per 1,000m, so it's 0.0312 Ohms.
The output resistance of a Devialet is 0.001 Ohms. So the cable would ruin the DF by 31 times. In other words, the DF would drop from 8,000 to ~560.
If the same cable would be used with amp. that has a DF of 500 (Emotiva typical DF) the actual DF would drop to half: 250.
The fact that such AWG wires are measure in 1/10 or 1/100 of an Ohm should not scare you. 
So a #0 AWG cable is not so thick as you might think, When DF goes high. I agree that it becomes dificult to connect the cable of such diameter to a binding post, 
but creative methods can solve it.
The improvement in sound worth the effort.