One thing that I am curious about is if upgraded power cables will eliminate the issue of my lights dimming when listening at reasonable high volume.
No. I’m 98% sure it will not. That is due to things taking place in the circuit. You may try a new breaker. But there again, I’m not certain. I was a carpenter/building contractor most of my life.I’ll leave the better explanations of why to the electricians
FWIW I will also correct @carlsbad on the size wire in the wall going to the outlet. It is 12 ga rather than 14. I’ve seen 14 used for light switches but not outlets
@hilde45 has a great idea. Each system is different. Some will benefit from PC’s Others will not