Can a power cord increase the resolution of an Class D (SMPS) amp by more than 5% ?

Last time I checked there was only one way to connect most all power cords. So that kind of makes directionality a moot point. You will never know if sounds better the other way or not. I would not loose much sleep over this personally but fret away if one must.  GK will be glad to help I'm sure.

Moops checks in with yet another silly comment, guess he’s bored and figures, what the heck, at least he can boost his already astronomical post count. Obviously the whole fabrication process must be controlled to ensure directionality is correct. Not only for speaker cables and interconnects but also power cords and Ethernet cables and HDMI cables. Hiding your head in the sand doesn’t make the problem go away, Moops. Let us know when you guys figure out what the term directionality even means. 

Pop quiz 
Of all the various audio cables and cords which ones are not AC? 

I told you the master of all things futile Geooks would be glad to help! Maybe he can help folks if their specific power cord is oriented correctly or not. Or maybe reverse it for you to find out. For a small fee maybe. Only fair....

Pop quiz
Of all the various audio cables and cords which ones are not AC?

Answer: nobody cares.

Audioquest or no, its quite impossible for a wire in an AC power cord to express any directionality. To do so would be taking on characteristics of a diode as George (+1), kosst (+1) and Al (+1) have all pointed out.

What *is* possible  is that the shield of the cable might be hooked up at one end or the other (as opposed to the ground connection, which is the green wire) which *might* make a difference somehow, and certainly the finished power cord has connectors at either end that tend to make it directional :)

Put another way, its quite possible to hear differences in power cords and to also confirm the differences through simple measurement. OTOH, its quite impossible to hear differences in the direction of AC wiring, and this is easily confirmed by the fact that measurement of such yields a null.

When someone suggests to you that a wire in a power cord has a directional quality, the best plan of action is to turn in the other direction and run as hard as you can.

Since Geoff has discovered this thread, it will no longer suit to continue posting to it or reading it as per usual; snake oil has a highly ephemeral quality and much of it will be applied soon, yielding a similar result as with a directional AC wire.