Why Expensive power Cables when Romex behind Wall?


Could somebody please help me to shed light on this?
Is there any reason I should invest in expensive power cables when there's low grade cable between my outlet and the wall? I've upgraded most other components in my systems, but I'm just not sure that spending several hundred dollars for power cables makes sense, when the cable running from my outlet to the wall costs less than $.10 per foot. Can anyone shed light on this?

Thanks!
boros
Bwhite's comments may be describing some of the differences I hear with premium power cables.

Nikkidanjo may be onto something where he describes cable shielding:

"Shielding the cables as they near this big rack of electronics may make all the difference. Perhaps the worst dirt is the dirt generated by your own system feeding back into itself. This could explain why shielding may help."

It may be a long wait before technology is developed that "proves" how some power cords work in our systems. Having heard significant improvements with several power cables, I don't intend to wait for a piece of paper telling me what I already know is true.

I have not tried metal outlet plates as Bwhite describes. I would not prejudge it effectiveness, until and UNLESS I tried it for myself.

I would likely believe in Mr. White conclusion, even if it failed to improve my system. Every system is different and it would be foolish to pass up an opportunity that at least one member has been successful with, especially one that costs about what some of us spend on a large soft drink.

I intend to purchase a couple of plates next time I visit Home Depot. Worse case I return them a few weeks later.
Thanks Albertporter! Please - don't expect the plates to make an improvement. They will however add a noticable and somewhat annoying brightness to your system. Hopefully this will help folks understand how mechanical resonance can play a significant role in what we hear in our systems.

Also, while you're at it, and if you feel like playing... the tightness of the screws which hold the outlet to the wall make a change as well.

After trying this with several outlet covers I ultimately decided to leave them off all together in my system. Having no outlet cover so far seems better than any other material.

Now if I can just figure out how to firm up that giggly junction box in the wall without tearing my sheetrock to bits.
Bwhite wrote:
"Here are quotes from Audioengr's "Technical Papers" - seems he is contradicting himself in claiming that resonance is for the most part not audible"

No contradiction. If you take the time to read the paper, you will see that I am talking about ELECTRICAL resonance, not mechanical resonance. I have extensive measurement and simulation data on this effect proving that it is real.

Mechanical resonance is a second-order effect at best. Electrical resonance is more of a first-order effect.

As for your metal outlet covers, I beleive that you are experiencing the placebo effect. There is no scientific explanation as to why this should make any difference whatsoever. Resonance requires a high-Q system, which this is not. Even if the outlet cover resonated, what electrical effect could this possibly have?
Nikkidanjo wrote:
"Basically, I don’t by the filter part unless some form of RF filter was deliberately added."

Agree 100%, power cords should not be filters, particularly on power amps.

The best analogy is that the pressure in the outlet of the pipe is the indicator of performance. If the pipe is 2" diameter for 25 feet and the last 6 feet are 6" in diameter, this will yield a much higher pressure at the outlet than if the pipe were 2" diameter the whole length. This is what happens when you add a low-inductance 6 foot cord to a 25 foot high-inductance wire in the wall. It really does work.
"Shielding the cables as they near this big rack of electronics may make all the difference. Perhaps the worst dirt is the dirt generated by your own system feeding back into itself. This could explain why shielding may help."

Sorry, but this is technically nonsense. Ask an engineer friend whether this makes any sense. You are mixing shielding from EM fields and mechanical resonances. Shielding eliminates susceptability to crosstalk from nearby EM or magnetic fields. It does not help with mechanical resonance.

"It may be a long wait before technology is developed that "proves" how some power cords work in our systems. Having heard significant improvements with several power cables, I don't intend to wait for a piece of paper telling me what I already know is true."

What is wrong with the analysis I just did above? It proves conclusively that lower inductance power cables reduce impedance to current flow by 22% or more in a typical home scenerio. Do you not understand the analysis?