Power Cables and Wall Sockets

@imaninatural 

"Without knowing for certain, it seems to me that power cables can only be as good as the in-home wiring coming to the wall socket. "

That's the logical conclusion.

@ghdprentice 

Like many others you say the last six feet of passive cable can make a big difference.  How?  Why is the last six feet different from the five miles or whatever of cable from the power station to your home and all the transformers, joints etc etc on the way?  Please explain in terms of physics how a passive cable can do this, absent active components and power conditioners that certainly can affect the quality of the power we receive.

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.

If the lights are on the same circuit as the amp, then probably yes.
If not, then you likely have something like a 40A service coming into an old house.

They have volt meters that plug into a socket, just plug it in somewhere else see what the voltage goes to when the amps kick.

If you amp is causing lights to dim you have an extreme power problem.  If the lights are dimming significantly, the circuit is overloaded, the breaker should be tripping.  The circuit is overloaded.  There is an increased fire risk.  Jerry

I believe 14 gage Romex is white , 12 gage is yellow and 10 gage is orange 

If you amp is causing lights to dim you have an extreme power problem. If the lights are dimming significantly, the circuit is overloaded, the breaker should be tripping. The circuit is overloaded. There is an increased fire risk. Jerry

We do not know that for sure…
I used to turn on a table saw and the light in the garage would go out when it started up.
(Yeah the birds jumped off of the wire with hot feet.)

But if there is 30A on a 40A feed from the pole, and only 12A on a 15A breaker, it does not mean a fire is imminent. That is what people use breakers and fuses for.

It just means that the voltage sags.