... abit confused: how does a power cord affect the presentation of sound...

It takes the sound from the amp to the speakers.

@nicotico , 
+1.
So much of this is system dependent, but so much is dependent upon the power cord's design.
I, in all honesty, never thought power cords would affect the sound of a system until I auditioned some AQ power cords. 

Bob

PCs are going to have less of an impact on the sound of your system than ICs or speaker cables. Optimize after those are set.

Not if you have such an oddball PC that has a characteristic that permeates the entire sound, which is what the OP has.

PCs are going to have less of an impact on the sound of your system than ICs or speaker cables.  Optimize after those are set.

CD Player is powered with a PS Audio Statement SC power cord, so I went in my closet and pulled out another PS AUDIO Statement SC power cord, hooked it up and expect to give it at least 5 days continuous re-break-in before serious listening.

That was your first mistake. If you want to learn about power cords- or any kind of wire, or anything for that matter- do your serious listening immediately. From the first minute. 

That is how you learn once something is burned in it doesn't take no 5 days to re-break in. It takes like 5 minutes. Okay maybe a little longer. Depends how long its been sitting around. But minutes to hours not days. Most of which is nothing to do with sitting around but because of all the wiggling and bending the wire went through going on and off. Something you can prove yourself. Simply take any wire that's been used without being touched a while, unplug and wiggle around, plug back in, listen closely immediately. Immediately! Because it only takes a few minutes to stabilize again.  

I know that interconnects and speaker cables would/could/Do affect sound presentation - but how could a power cord? 

Your second and much bigger mistake, thinking how matters. How is a story with many parts, chapters, volumes. How is Alice in Wonderland. The more credence you give to how the more they will be yanking you left and right, up and down, back and forth, because after 30+ years let me tell you "how" is The Neverending Story. Everyone has their own favorite how, and however good their how is now the one thing I can absolutely guarantee you is if you wait a year or three it will be completely different. 

That's one angle. The other one is, why do you think there's any difference between the power cord and the interconnect- or the speaker cable? Is the signal only in the interconnect? Really? So the power comes out of the wall in one absolutely unvarying fluid stream? I don't think so! Power draw pulses and fluctuates right along with the demands of the music. Think about it.

Cleeds

... Thanks so much - with 3132 posts, I appreciate your suggestion - oh, and thanks for sharing your expertise on the topic. No experience/opinion on this?

Here’s the best place to start, select electricity and magnetism.

http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

There are many existing threads about power cords.
Here’s one.
Here’s another.
And another, with nearly 500 responses!
Aaaaaaannnnnd another.

And so many more. They might be a good place for you to start.

Ok - that particular line of power cords by PS audio - the “SC” series - the jacket was impregnated with ferrite. While intended to reduce noise, ferrite also has the negative side effect of quashing dynamics resulting in the sound being “slow.” Pretty sure PS audio even admitted this flaw later, and ceased impregnating the jackets with ferrite on their subsequent line of power cords. Would use those only for video applications, or maybe something like a transport. Would not use those on a preamp or amp where the “slow” sound will be most pronounced. CD player/DAC - questionable. I know this from personal experience with these power cords. Most power cords for high end audio applications avoid the use of ferrite; you see ferrite donuts on a lot of power cords that come with computer equipment and other small appliances. Hope this helps.

My experience is that the better power cord gives me less electronic hash, more intense tone colors, and more three-dimensionality.  These differences aren't night and day, but I'm far from ready to dismiss power cord upgrades as snake oil.  I've never noticed the slightest difference with rhythm and pace.

insearchofprat,

It's really hard to explain without being technical.  Without a technical background, it would be hard to understand even with a good explanation.

No consensus to be found on practically anything related to the topic of audiophile power cords.