Ideal power cord lengths?

I remember reading an interview with an upmarket cord manufacturer. Asked whether high priced wiring really sounded better - he said 

"Yes, in the same way your car drives better after it has been washed and cleaned"

@oliver_reid +1

pennfootball71,  I change some of my AC Cable positionning, and your tests reveal me something, I wonder if the difference is not necessarely the brand, but also the lenght,  a 1.5 m is better than a 1 m on my power bar.  Thank you.

OK, so how about this: you bought a great amp from a reputable company and they sent you a power cord with it... HOW ABOUT just use THAT one? Would Marantz send an inferior cord with the Ruby? I don’t think so.

@curtdr The answer is yes, they would and do. You’re missing the fact that after retail markups including a better PC would add significantly to the price of a product. Plus, cables are also notoriously system dependent, so it’s possible that an expensive PC wouldn’t synergize with a customer’s system/tastes so they would’ve paid all that extra cash for nothing. Then there’s that more serious audiophiles often have their own preferences for PCs and would likely never use the cord that came with the equipment. For all these reasons it makes sense for a manufacturer to include a cheap cable that’s good enough to do at least do justice to the equipment and let the customer choose what PC works best for their tastes/system. If you were right then manufacturers would be providing better PCs with their products, but they don’t. I’m not aware of any that do and everything I’ve bought has come with the generic black cord. Have you ever seen a manufacturer at an audio show power their products with a generic black cord? I think not. They pay a lot of $$$ to have their equipment at shows, so if the generic black cord was their best option they’d use it to show their products at their absolute best, but they don’t.  Hmmm.

@soix 

I'm not missing the fact that an expensive power cord adds to cost.

I am extremely skeptical that the power cord supplied with a Marantz Ruby, to continue the example, is a detriment at all to its audible performance.

Hey, if it makes one feel better to swap out a cord to a more expensive one, well then do it and feel better.  That's fine, I guess...  but I don't believe it's a wise efficient use of funds when it comes to upgrading for sonic performance, unless it's the one thing that would make one feel better, sleep better, whatever, and that's on you and it's fine.

However, I stand by my overall message of high skepticism, except maybe in extreme cases of crappy or lower level products in the first place but then why would anybody invest more into an inferior poorly-designed overall product?  If the power cord is a problem, why would you trust the product or the company in the first place?  

I suppose one possibility, but it would be a relatively rare one, is if there is some extraordinary electrical weirdness in your home and you need some sort of super shielding, but I've lived in many places of this country in a variety of towns and cities and have never seen it personally except for one house where I had subwoofer hum.  And, if you do detect weirdness, try just plugging in to a different plug, which is a simple solution that instantly solved a subwoofer hum problem that I used to have when watching TV.  I just used a modest "indoor/outdoor" extension cord of adequate length to get the subwoofer onto a separate circuit in the house, a plug controlled by a different breaker than the TV was on, and voila, problem solved.