Can POWER CORDS really make that big a difference?

Try and see, buy where you can return.
Personally, I was surprised they made a difference, yet there it was. More stuff to spend money on.
But first... change your wall outlets.

KP

In my limited experience, I found more of a difference with my amp than my CD player, at least with the power cords I am using. (LAT International AC-2)

Sure. I found that some had a noticeable effect and others appeared to have no effect from stock cords. I also noticed that the effect was similar with amp, preamp and cd player with each cord. Each apparently has a sonic signature. Silly but it does work most of the time.

I would spend the money on power devices that will make a difference such as PS Audio power regenerators, etc. Other than that have all the light dimmers revomed in your house. If you can not have your neighbors to agree to do the same, then have your power company run a direct line to your house from your substation. There, you will hear the difference.. of course, IMHO.

In a word, yes.