No one actually knows how to lculate what speaker cable they need

I have tried many cables to drive modified Magnepan MG IIIa’s with a Pass Labs 250.5.  The best so far are DIY five foot cables made with 16AWG .999 pure solid silver inside 1/4” poly sleeve connected directly without termination to amp and speakers.  The two leads per side are keep 2 1/2” apart from each other in a ladder design.  Every 12” a three each piece of plastic plumbers strap is fixed to the cables with zip ties to keep the cables apart.  Total cost: under $7 per foot ($70 for for two five foot cables).  The sound is holographic.  Best bass these speakers have ever produced.  Very revealing mids and highs, particularly with DSD recordings.

Happy listening.

8 Ohm nominal speaker impedance +
0.0256 Ohm cable resistance =
8.0256 total nominal amp load.

Amp output impedance 0.016 Ohms
DF (which is a ratio, not units) into 8 Ohms is 8/0.016 = 500
DF into 8.0256 Ohms is 8.0256/0.016 = 501.6

Big difference. Not.

Hi there . For me every thing is simple. Top line speakers as well as amp ,power amp, preamp, cables and ofcours most expensive on entire world . And no question, no more arguments . It must sound good. I might invent something exceptional something extremely good sounding, but who is going to admire it , I got no name. We already have a gurus who are on the top. I should maybe write, money talks as simple. Thank you , nothing to argue about.

Poor wording on my part.  No the cables do not calculate.  The company measures all of your components' parameters and the company builds a cable with a network that that takes all of those factors into account.  Now your search is over.  Sorry for the ambiguity.