Use to metric but would think for a short length 4 awg, would be up over 100A no probs.
Ok electrician short course 101.
Ratings has a good deal to do with the insulation, are mainly to do with not burning down buildings, high current in under sized long cables also causing volt drops in installations affecting installation.
For short lengths of cable ratings are higher.
If insulation does start to bubble which doubt it would even think about even for audio wire, just strip off the insulation altogether, untwist the strands and it'll be good for 300A then.
You'd probably be concerning yourself better with loose fitting connections heating up and dropping volts.
That switch looks sex chocolate now you've cleaned it nice Frankenstien would be pleased Muuuuuhhhhaaaa.
I make my own 100A switching setups out of copper flat bar, nothing better.