Power cord question

[John Roman]

How is it that a power cord can make a difference in the sound of audio gear? Here is what I think is a common scenario. You plug in three pieces of gear, say a pre and some mono's, using some fat well made power cords. All the cords are 10 awg minimum, stranded 6n copper, generally better than what you get with most gear. But here's the kicker, you plug all those cords into a supply circuit that typically is 12 awg solid core romex. To me it seems the crucial factor is that supply wire, its quality, size how it's run etc. I realize that each component is only drawing a couple amps at most (for tube gear) and that the supply is most likely a 15 amp circuit. Even if the rest of the supply circuit is not being used you're still drawing against the romex. I see monstrous power cords at high end audio stores and at shows all the time----- plugged into a standard duplex $5 receptacle. It's IMO laughable when you consider the astronomical prices charged for these "quality" cords.  I also understand that as a DIY community of builders we are motivated not only by reasonable cost to value  but I suspect also by a realization that a lot of gear is just over priced. Please enlighten me on this subject.

[HF9]

It's exactly as you say, in fact I think NEC code is currently 14 gauge for 15 amps. The quality of the wire in your walls is probably low cost romex.

That being said, swapping out the cheap 18/3 made of low quality, low cost PVC dielectric with something halfway decent (PE / PTFE) will make an audible difference. Also depending on your setup, a floating shield can help. Having a thicker wire will also increase capacitance, which can cause perceived differences.

Would I ever buy a $200+ power cord? No way, but I'm not going to be using a $2 one either.

[Doc B.]

I think the most likely possibility is that the cord is acting as a filter of some sort. What it's filtering may be different for different cords.

[howardnair]

do power cords make a difference-to a certain degree, yes-as doc says they most likely act as a filter-the one thing i have done is a dedicated circuit using 12/2 shielded twisted wire direct to the panel-the other circuit i was using -even though not in the same circuit as the furnace was picking up the click when the thermostat tripped and untripped-the dedicated circuit of shielded wire eliminated that and probably some other noise-romex is not junk , it is  a good medium to carry electricity-though not set up for rf shielding -i have yet to buy a $200 power cord -i own one -a cardas something or other-i find no difference in that vs the one doc sent, the other ones i made-especially the one i made using the braided method via doc but used, silver teflon wire, braided-with marinco ends-here is a prime example of what john is stating
http://www.dedicatedaudio.com/inc/sdetail/125/24044-a hospital grade outlet will help -having a  slightly heavier tang for better contact-john, i don't think this enlightened you but i have drank some coffee and shared my not so humble opinion-howie

[Grainger49]

I try not to worry about how it makes a difference but what difference it makes.  I'm an EE.  A number of things I have heard in my audio life haven't made sense.  I have come to accept that they change the sound and determine if I want what they bring to the table.