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

I believe Transparent Cables does just what you ask - they take all of your equipment parameters and calculate the "perfect" cable specs for you. See? Your search is over.

+1 morg111! What the heck b4icu is spouting is NOT SCIENCE!

Example (one of many): "Unfortunately, most speaker cables are of 14-12 AWG and with some length from 8' to 24'. For the length, by increase the length from 8' to 16', in order to keep the same resistance of a cable, the cable's cross-section needs to double. For 24' length it needs to triple and so on."

No. That is not correct.

And the cable does not contribute to the Damping Factor (DF).

Resistance in an 8 ft length of 12 AWG copper wire is INSIGNIFICANT! 

Mr.  chayro
How old are you?
Cables calculate? If they could also cook we could merry them.

morg111, invective aside, is a truth-teller. The article he cites, http://www.roger-russell.com/wire/wire.htm, is science combined with common sense, and a real money-saver. All that said it makes sense to take care (or pay some company some tens of dollars to take care) with the end connectors to amp and speakers.

Even if could connect our amp to speaker terminals with 1 inch square (cross sectioned), or other rectangular profile, six nines, pure copper bars with only air as the dielectric, there would be NO improvement in sound. None, zilch, zip. Arrrgh!