Replacing stock cables: where to start

Jeff_jones, I found that difference between power cords on a certain component depends on several things. Just to name a few:
1) the overall resolution of the system
2) the quality of power supply in a given component.
3) room acoustics(which also contributes to bullet #1)

also, just how much different a given power cord will sound from a stock cord on a given component also depends on what aftermarket power cord are we talking about.
Example: you will hear bigger improvement over a stock cord with, let's say, a Shunyata Anaconda Helix, than you would by comparing the stock cord to Zu Bok.

Difference between power cords could be as obvious as between interconnects. Things like bass, midrange, instrument separation, air, soundstage, are all affected by cables, including power cords. Also, effect of power cords is cumulative. If you change one, you get certain amount of improvement(with the right cord that is). If you upgrade all, you gain more. Same as with interconnects.
This has been my experience in my system. As we like to say here on the 'gon, YMMV.

Audphile1 - No issues here. I suspect, but don't know, that the reason power cords are not a worthwhile investment to me is your item #2. Most of my equipment has pretty robust filtering, by the time the ac gets all the way to the dc buss it has seen two or three filter networks. If I had equipment designed with sort of the minimalist/purist approach it might well be more sensitive to ac input variance. The other thing that might be hiding power cord effect is that I've got components plugged into line filters, so any gain you get from a cord acting as a bit of a filter network to keep component 1 from creating ac hash for component 2 is probably dealt with in the filter. All that being said, I really do believe that a lot of people would save a lot of money if they would test things in at least a quasi scientific fashion to eliminate hearing what they think they should. Often when you notice that "a veil is lifted and I can hear things I've never heard before" , or some such, it is because you are concentrating more when listening to the new gadget.
Happy Listening!

Sorry Jeff, but I disagree.
Filtering alone doesn't explain everything. Have you considered that your powerline filters may be choking off or reducing the instantaneous bursts of current that produce the superior dynamics that great PC's are capable of? I use only small amounts of mostly parallel filtering on my AC, and the differences between outlets, AC connectors, and cables is very obvious. Since nobody seems to be arguing that outlets and connectors are 'filters', then what explains the large differences I hear? Filtering is only part of the picture, instantaneous current delivery is (imo) even more important.
I'm not saying everyone has to invest in kilobuck PC's, but putting flimsy 16-18awg cords on high-end gear just seems penny wise and pound foolish to me.
Oh, and I 'concentrate' on my listening all the time, that's what makes me a genuine audio fool!!!

Jeff_jones, I use power line conditioner as well and the effect of power cords is obvious on the front end components.

There are few ways to compare components and wires. I find it most useful when I go back from a better/"upgrade" cable back to my current cable. For me, this is the most sober way to tell the difference. It is not when you go up, it is when you downgrade that you will feel the difference. I decide if it is worth it or not by what and how much I am missing from an "upgrade" cable and whether or not I can live without the things the upgrade brings.

If the upgrade is not worth it, then it is what it is.

Now let's get back to the original question of this thread, which you didn't address in your post at all.
Blind testing power cords and other cables has been chewed up and spit out on the audiogon and other forums enough times. Scientific test, measurements, all this BS has already been debated.

You hear what you hear. That's what counts. Your system, your ears.

Audphile1 - If I didn't address the question my apologies to you and the author of the post. I agree with your statement that you hear what you hear. My advice is to try the cheapest cords you can find of sufficient gauge, test them against any cords that suit your fancy, and do a blind test to eliminate the psychological component of the audition. This will either resolve doubt or save a chunk of change. IMHO.