I've used the same cables for years--be they connecting to cheap speaker/components or to 1KW pro audio gear
Yes, I've hooked $40 Rapco professional speaker cable to a $20 chip amp--sue me!
Then again, I've built speaker cable out of 12 AWG extension cord connecting $1,000 plus amps to $1,000 plus PA speakers in a pinch so what do I know?
Jesus and Allah demand 10 percent of your earnings so it makes sense to blow 10 percent on wire--right? Uhhhhh, do you want what works correctly or what your flavor of sky god demands? 12 AWG two conductor copper wire should work for home use no matter what amps, watts or flavor you demand--good starting point.
For me, my old Rapco 12 AWG cable has been run over by vehicles, ran the PA system for years withhout problems so I used it for my HT system without a second thought.
If you plan on running SpeakerPower professional 240 volt 8KW amps at 2 ohms, might want to go with 10AWG two conductor cord--if not 12/14/16 guage is your friend. For me, using 12 AWG has not been an issue for the past 25 years as long as I don't go below 4 ohms and 50 feet.
For home use with runs less than 50 feet, I'd look at 14 AWG zip cord--if you plan on running below 4 ohms, then it becomes a matter of what impedance, the length of the cable and power applied. Good luck with your build, get the correct guage out of the way first, make it copper wire of the correct guage and enjoy your hobby. There is no percentage, there is the proper guage of copper wire depending on length, amp capacity and voltage.
12 and 14 guage for most home installations is overkill but it is the cheapest component and lasts for longer than you'll be breathing so you'll be fine with a bit of overkill. Enjoyy running the cable...part of living the dream.