Ideal power cord lengths?

@curtdr - They are only inferior if you're concerned about sound quality. But to your point... Stock power cables will certainly power up the component. 

@boxer12  -  Color me deeply skeptical. 

I don't believe those companies, or any mid to high enders, would scrimp on the power cord if such a scrimp degraded sound quality, especially of their top models but really mostly through the line.  Certainly somebody along the line, in the engineering team or quality control or otherwise, would have spoken up if after all the care and expertise they took in designing a product such as the Marantz Ruby... or take your pick, Accuphase 480, Luxman, whatever.. then the supplied power cord degraded all that work???  I don't think so.  They wouldn't pick a random cord and throw it on.  They would use one that works and works well without degrading the capabilities of the machine.   

If you are bothered by a 5' or 6' cord as too long or too short, well I can see swapping out the cord and making sure you get one at least the equivalent of the supplied cord, to get one of a length you need and leave it at that, if you are concerned with cable management and want to tidy everything up.  But as for sound quality upgrade?  Nope, I don't believe it. 

Some may call me naive, and some might call me critically skeptical: take your pick.

I completely get why it’s tough to make sense of things when it comes to HiFi. I get it; I have an engineering background, and nothing in HiFi makes sense. In this hobby common sense does not apply, and is often inaccurate. The fact that a USB cable transmitting 1’s and 0’s can make difference is absolutely preposterous to me, even moreso than the fact that power cords matter. A system assembled through a practical, common sense approach will not get you far, in my experience.

To me this hobby is all about using your ears, preferably through objective, double-blind testing of one component at a time, on the right type of system that will reveal differences the component being tested makes, is what ultimately matters in this hobby. It is all that matters in this hobby. Other than your budget!

it is important to validate results through double blind testing if at all possible.  If not possible, I know enough to distrust my own perceptions enough to really question what I think I am hearing, and only make an assessment after many weeks of comparisons.  Many prefer to use a new component for weeks or even months, before going back to validate the difference it makes.  A/B testing is SO difficult because human auditory memory is absolutely terrible.  By the time you’ve connected a new component your perception of what you just heard before will absolutely have shifted.  It’s even worse if someone talks to you between tests.  That’s why double blind testing is so efficient and effective.  If you’ve not gone through this process, you are left only with common sense, and the rules that govern our world do not apply to HiFi.  Those who apply common sense will disagree, of course!

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