What was the first power cable that you noticed a difference in the sound?

@tennisdoc56 

I tend to agree with you that there is no valid scientific explanation re: much of the wire claims.  That said:

1.  Several sub assemblies (e.g., transformers and most digital products) spit out a lot of noise that can, indeed, travel back through the mains. (Bringing up the need for isolation at the plug, which is a different topic)

2.  Quality insulation helps the noise from going somewhere unwanted.

3.  A lot of supplied power cords do skimp on copper gauge and nice fitting plugs.  Electricity and interference will take the path of least resistance.  So a low (by which I mean bigger) gauge wire provides an easier path.  I’m not opposed to the idea of a high gauge wire might be starving a component for a bit, either.

4.  Nice wires tend to be bought longer and are more flexible.  So people take more care with routing of interconnects and mains so they cross at 90 degrees and don’t run close parallel, which also helps with interference.

5.  Tight fitting plugs make a better connection.  Hence why hospitals use hospital plugs.  
 

Note nothing here discusses magic crystal wire with unicorn hair.

Just low AWG wire, with good copper, nicely insulated (say, the kind the IT guy buys for  your company router) and perhaps a secondary sheath, of generous length for proper routing, with hospital plugs.  Not cheap stuff, at all.

Different, but related, issue:  components need space and isolation.  They all generate all sorts of noise.  The interactions are so complex it might as well be voodoo.

Source:  I was an electronics countermeasures officer in the very first Gulf War hunting SCUDs in the middle of Iraq from a POS Kiawa helicopter with no weapons packed with finicky electronics.

I am also struggling with this conundrum, but I gotta side with this response from a different forum....

":

If someone is selling a product with faulty/inadequate power cables, I'm pretty sure there would be recalls and/or lawsuits.

Rather than a safety concern the scam artist's sales pitch says things along the lines of "The inadequately thick (meaning gauge) cord they gave you for free is choking your amp from receiving the full current in needs to provide you with the punch and dynamics your amp is actually capable of". See their story is the necessary cable is "Just too darn expensive for them to give you and still sell the unit at a competitive price." What they count on is that the typical consumer has no idea that thick power cords are actually a relatively trivial expense to the maker. All they see is that Monstrous Hype AC cables are expensive so that's their frame of reference.
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To the general audience now.

The notion an amplifier maker has the wherewithal to design a competent amplifier but either due to incompetence or malfeasance only supplies an inadequately thick (gauge) AC power cord to provide maximal performance with it (considering how incredibly affordable they are when bought in bulk), is laughable.

The aftermarket AC power cord industry is predominantly a scam. Sure if you lose the original cord, need a longer one (which if significant may require a bump up in gauge), or think the appearance matters because you've been told you should, fine. But the sound does not change.

THE LAST LINE SAYS IT ALL!

@polkalover Broad generalizations such as you promote are not universally true.  In many situations a power cable change makes little difference because the are problems or performance limitations in other parts of the system.  As another post described extensive experience setting up an entire system for minimal noise floor, same system approach should be applied to home audio.  That approach does not mean expensive cables of any type have to be used.  Quality matters.  Everything matters.

If one person is happy with manufacturer supplied cables - FINE.  If another wants to spend THEIR money and time differently - FINE.  Manufacturers are in the business of making money and staying in business.  Assuming anything else is ass -u-me, as the saying goes.

NASA and the Air Force learned when first trying to launch things into space, unexpected things happened.  Well designed sub-systems did not always behave as expected and failures were frequent.  Eventually smart people discovered unexpected and unplanned circuit paths, i.e. sneak circuits.  A sneak circuit analysis discipline evolved.  Other analysis disciplines evolved that are incorporated, to some degree, in modern electrical design.  However, make no mistake that cost remains the primary driver when it comes time to stop the engineers and go into production.

Does everybody need a $200, $1000, $10,000 power cable?  Absolutely not.  Is there a lot of smoke and mirrors justifying some high dollar cables.  Yes, but not all.  There are well engineered and constructed cables that will make a difference when part of a system level approach.  The only universal truth is the personal freedom to make your own choice.

@texbychoice   Jack Bybee's work as a physicist would be an example cable/circuit research for military use.

Bybee’s first commercial products emerged from Cold War-era military-industrial research. The stealthy shadow contest of nuclear submarine detection, location and evasion demanded ever-quieter circuits, lower electronic noise and greater signal-to-noise ratios. Practitioners summed up the problem as: “reducing 1/f noise, from DC to 2000hz”.  

Bybee’s technology involves exotic blends of rare-earth metals or their isotopes to reduce electronic noise in circuits. In the mid-1990s, Bybee’s AC filtering was among the first of its kind to use exotic doped materials instead of transformers or balanced power, which made it a novel concept at the time.

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More examples would be these engineers who started - and continue to run - innovative audio cable companies.

Purist Audio Design – Founded by Jim Aud – EE & Physicist

From there, I earned my Electronics Engineering degree at Brescia University, and would later study Computer Science for almost two years at Westinghouse. Then I came to South Texas Nuclear, and studied what they’d call today nuclear physics. Link here.

Shunyata Research – Founded by Caelin Gabriel – Research Scientist

Caelin Gabriel is a former US military research scientist with a background in research and design of ultra-sensitive data acquisition systems.  These systems were designed to detect extremely low-level signals otherwise obscured by random noise, requiring years of intensive research into the sources and effects of signal and power-line noise interference.  Link here.

Bybee Technologies – Founded by Jack Bybee – Physicist

Jack’s science and physicist background gave him the understanding about negative effects of quantum noise. Link here.

Silversmith Audio – Founded by Jeffrey Smith – Engineer

CEO/Designer Jeffrey Smith is a Wyoming native and graduate of the United States Naval Academy with a Bachelor of Science degree in General Engineering. He also earned a Master of Science Degree, With Distinction, in Defense and Strategic Studies. Link here.

MIT Cables – Founded by Bruce Brisson – awarded 20 USPTO engineering patents.

MIT Cables founder Bruce Brisson began purposely designing audio cables in the 1970’s after encountering the sonic problems inherent in cables typical of the day. Link here.

Audioquest – Garth Powell - Sr. Director of Engineering

Formerly with Furman Power for 12 years.

It is when reading about Bybee 12 years ago that i decided to experiment with some minerals as shungite and quartz etc ... With success at my modest scale ...😊

I dont have money for costly tweaks but it does not means they dont work ...

Science is experiments, not decrees by some Pope of a technological cult faith about how and why qualia are only reducible to Maxwell equations as interpreted by some engineers ..

One of the greatest science achievements of all time come from mystics rigorous thinking by the way ... Sorry for technocratic materialists ...

life is not simplistic ... 😁

@texbychoice Jack Bybee’s work as a physicist would be an example cable/circuit research for military use.