Does a Good 20 amp cable Make a Difference

In my mind, it would seem that as long as your power filter is not hungry, and is getting all the amps and joules it requires, that just applying a more expensive cable of the same size would be negated by the filter. If it did make a subtle difference, then the filter would do its thing, and the same result would be present on its output. I'm sure you've heard the theories about how modifying the last 3 feet of a wire than goes back to the power company, and all over the neighborhood, is just wishful thinking. But what comes after the filter! Now you've got control over that! Keeping that clean signal you've created intact with large enough conductors to prevent any restrictions into your gear, I can fully see how quality wires can help! But, this is all supposition, I would be very interested to learn if indeed you did hear a difference by upgrading that cable. What we think is happening, and what actually happens can often times differ, there are variables we are not measuring involved, otherwise no wire could make any difference. What was that website? The Cable Company, I'm not sure if they still do, but they used to have a loaner system that allowed you to try cables in your system, and return them if they weren't right for you. I just looked and they do have a slew of power cables available. And of course I'm sure you'd get better prices here on Audiogon, and just buy and resell any that didn't please you.

I know I've heard others say and swear that their filter's power cord made noticeable differences, and I've heard just as many others say the opposite, no way to know except conduct your own experiment!

Since you find the Shunyata power cords improve the sound of your system, it stands to reason that you think Shunyata knows what they are doing. If so, their advice is to put the best cord you have between your wall receptacle and their filter/conditioner. What is "best"? In this application, the heaviest gauge, I would imagine, and the one that provides the most filtering secondly. You can pick up a (used, of course) Copperhead (10 gauge) for under $200 now.

Shunyata has stated that the most important power cord is the one feeding your Shunyata Power Filter. I agree as others have said in this post get the best power cord you can afford to run from the AC outlet to your power filtration system.
And in my opinion, good power cords do make a difference.

I definitely have found that regardless of manufacturer of cables that I was using at the time, that the quality of the 20amp (or 15amp if applicable) powercord between the wall and your power conditioner absolutely makes a difference. Please do stay away from powercords that do their own filtering (IMHO); what you need is the best cord possible bringing the best power to the unit, just like your front-end and amp/pre-amp components.

Now seeing im presently using a/c cables that are in the $400 $500 $600+ range.Would it not make sense to go equally for a great 20 amp a/c cable for the the power filter?

I agree with the others that it can make a difference, and that there is likely room for improvement. However, I would not by any means assume, as you appear to be doing, that a similar price = a similar level of performance in your (or any other) particular system. Or that higher price = better performance, for that matter.

See the comments by me and others in this thread, and this one, and this one, among others.

As was suggested above, you may want to consider using the "library service" of The Cable Company to try out a variety of power cords at various price points.

Good luck. Regards,
-- Al