Just for the record, the most ordinary copper wire in the electrical industry, has by standard a purity of 99.98%. So no matter how much of an effort or price is added, it worth only 0.02% in conductivity (resistance). Moving from copper to Silver, that is agreed to be the best conductor from all materials, Silver is only 5% better than copper but costs (crude stock market price) 130 times more.
Adding 5% in the copper wire cross section, would equal it to the silver wire...
So, as I see it, this is not the light to look under it, for the missing coin.
DF is about control. The ability of the Amp to drive a compex speaker coil, that is also a generator, objection equally the current caused it to move. Add a crossover with some C and L.
When DF is low (as the case with tubes), the Amp’s designer, by intention, gave up that quality. Tubes have by nature low current and high voltage. All tube amps use an output transformer to convert that into lower voltage and higher current. Some, like McIntosh use such topology even with their SS amps, to achieve a tube like sound, without using tubes. Keep in mind that most speakers impedance is 8 ohms, so at 2.83V they consume 1W.
For that reason, the serial resistance that the speaker cable add to the Amp’s output resistance is insignificant with a DF=20.
It’s more significant when DF=200 or 800...
When that parameter with SS amps, and DF>200 is achieved, it provides clarity and better bass. Tight and clear.
Such would have a positive effect on the mid and highs, as they get a release from the "heavy bass".
Well, the formula suggests an improvement from thin cables till the calculated value is applied. When that is increased, above the calculated value, sound remains the same. Only the cable is getting more expensive and difficult to build. This been tested with my friend’s system (B&W801D with 250W Pass lab’s power amp with DF=200). I calculated his cable to be of #4 AWG and 3m long and built one for him. Some time ago, after completed a demo cable of the very same length (3m) but #0 AWG, I put it to test and compared between the two: #4 AWG vs #0 AWG.
As predicted, there was no improvement or degradation in sound. They sounded identical.
So unless you use some cable with a twick, like MIT with a box or similar, getting thicker should not effect your sound.