Power Cables and Wall Sockets

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!

Installing a dedicated 20 amp circuit for the audio gear will help with the lights dimming. Probably eliminate it.

Mike

Run dedicated lines.

Or spend a couple of grand on a re-generator like what PS Audio offers.

IME they’re additive.  Add a better PC, you can get better sound.  Add a better outlet, you can get better sound.  Add both and you get even better sound.  I’ve said it over and over, but in this hobby EVERYTHING MATTERS and makes a difference.  And a big +1 for dedicated lines.  

If your light dim briefly at amp turn on, that's pretty normal. If your lights are dimming when using the amp your circuit is borderline overdrawn. You need to look at how extensive the line is, what other components are on it etc. A dedicated line could be helpful, a new power cord not so much. One way or another you need to lessen the overall load on the circuit. It is possible too, the outlets in the circuit are inferior and not send the "signal" very effectively. It is very much worth upgrading plugs in any circuit just to make for more robust connection etc.