AC cord polarity?? Does it matter???????

Metro04, you are correct in your basic evaluation of the situation, but yes, you are missing something, and that's the damn power company!

As the article Jea48 mentioned above illustrates, the power company uses (literally) the ground for its return leg to the generator. Which means in normal 120V house systems, the neutral blade is not always at zero potential relative to ground (in fact I've never found it to be so.)

So it's not the component's fault exactly, but depending how a components (power supply) circuits happen to be oriented to this "ground leak" current will mean slightly more or less noise (usually 60 cycle hum) in your system.

Balanced power units simply eliminate this problem altogether.

Hsgarch,

Thanks for getting back with me.

Even if the neutral wasn't at zero potential, most domestic voltges provide more than adequate supply for most component DC rails and regulated circuits (+/- 0.5 to 1.0 VAC of the localized incoming supply, which can swing pretty widely throughout the day, and per region).

In most homes, aren't the neutral and "ground" combined within the breaker box? This SHOULD place the N and G at the same potential, thus supplying the proper circuit voltage into the component's isolation x-former.

Now, what happens to so called "leakage inductance" within a non-ferrous chassis (aluminum)? What about components utilizing un-grounded chassis (2-prong cords), or a combination of the two? If none of the component's circuits are electrically grounded to the chassis, what are these stray voltages going to affect? In a ferrous chassis, I can see some 60 Hz magnet issues affecting certain circuits, but not with aluminum. Any minute x-former leakage would stay localized around itself. Right, or what?

I'm just concerned about blanket statements towards these wiring orientation claims, and whether they are indeed audible in most scenarios.

Your responces are always welcome, and I'm not trying to be argumentative. I do have lots of electronic background, but claim to know everything.

Metro, the answer to:

"In most homes, aren't the neutral and "ground" combined within the breaker box?"

Is no. And this is very important to understanding the "leakage" problem oulined in the article you cite above.
The neutral is zero relative to the 120V on each side of it. But it is not zero relative to earth ground.

So depending how the power supply in a component is laid out, connecting one of the two AC plug blades to neutral will result in less ground current leakage through the "neutral" leg of the power supply circuit. As a matter of fact, that is why, as someone described above how to measure for the best plug orientation, they specifically mentioned not to connect the ground pin of the AC plug when doing the measurement. To which I'll add two more rules: turn off the component, and disconnect all other connections to the component (ICs, spkr cables, coax cable or digital feeds, etc) because they may be connected to ground somewhere on their other ends, and you don't want that.

The idea behind this testing procedure is to "force" current that would,in grounded components, ordinarily drain to ground, instead to "leak" through the neutral so it can be measured. And then minimized by choosing the proper plug orientation.

So why is doing this a good thing? Because when everything is hooked back up, some current will drain to ground through the ground leg, and every one of these conditions in your system represents a ground loop which increases the baseline level of hum (and sometimes noise) in the system.