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

They don’t make difference unless the gauge is too low and they are starving the component from power. Higher price tags and pretty packaging won’t change that. 

@tennisdoc56 +1! At last a reality-based response! 

from  tennisdoc56: By what method/electrical theory does a power cord improve the contractor grade romex in your walls?   Please avoid explanations in biology such as sees, senses, feels, prefers.   Not being sarcastic 

I googled the following:  "acoustical properties of various metal conductors" and over the next 6 pages, I didn't get a single hit that covered, in any manner, the way that each metal affects the sound of the signal that passes through it.   There were entries about sound absorption, sound reflection, which metal is the best conductor of electricity, acoustic properties of commercially available thermal insulators, and the speed of sound in metal/sound waves passing through solid metals.   

Nowhere did I see any mention of how passing the signal through various metals affects the sound.  There was nothing about the warmth of gold, the detail of silver, etc.  Is there respectable research being done in this area; are theories out there relating to this?   I have no idea, but my search didn't yield anything relevant.   I'm not a scientist.  I'm actually quite challenged by modern technology, but I do use the scientific method in my audiophile pursuit.  I LISTEN.  I try different components, cables, connectors, and most recently, slugs (in place of fuses).  I don't know WHY there are such variations in sound between the various metals I've used but, clearly, the addition of different metal(s) in the signal path (and possibly outside in the case of some fuses) can significantly affect the sound.  

Rather than rely on this stance, why don't you simply experiment, and listen.  Do you really think that all those stating the benefits/differences of cables are delusional or just exaggerating?    And please tennisdoc56, don't take this as an attack.  Since the research doesn't appear to be out there, I think we should all do our own.  

I can say the days of OCC Wire are now over in my system due to my adopting the use of PC Triple C Wire.

I have been an advocate of PC Triple C Wire for a period of time and have been instrumental through loaning out Cables using this Wire. I can assure you that some very enthusiastic users of Audio Equipment have now moved to PC Triple C Wire used throughout their systems following their encounters with it in Loaned/Demonstrated Cables. 

One such encounter was with Power Cables, I loaned a PC Triple C Wire Power Cable with a Purchase Value of approx' £200 per metre, to a individual who has a lot of respect throughout the UK. The individuals system receives very good appraisal and the work they carry out on Audio Devices as work for betterment is very well known. This person has a lot of friends with Audio Interests.

The initial experience of the above individuals experiencing PC Triple C wire was with myself present. I was keen to hear it in use in a System not using Valve Amplification and the system it was to be added to is SS Amplification. 

The owner of the System, put a current through the Cable for approx' one hour before the demo' took place.

On adding the Cable to the Phonostage, the effect was immediate and to both listeners there was a more to be heard on offer and each track played was  assessed as a betterment.

Very Similar happened with the Power Amp.

It was agreed on the day that my choice of Plug and IEC for the Cables were able to be improved upon and more could be expected if this was addressed.

I left the Cable with this individual to swap out connectors and further assess.

The assessments went further than I thought would occur, a local group got involved and purchased other types of Power Cable produced using PC Triple C Wire.  

The A/B Comparisons took place with a Group present at the system I loaned the Cable to.

The out come was quite interesting, especially allowing for the follow up evaluations.

The Group were all in agreement that the Cable seen in the Link, when terminated with Solid Copper Plug/IEC had an impact on the sonic being produced, that was a betterment to the previous Power Cables in use.

 https://zenmarket.jp/en/rakutenproduct.aspx?itemCode=audio9:10000582     

As sure as some cables change the sound qualia as perceived by some brain , it is sure also as in the case of some power conditioner , they can degrade the quality of sound or improve it for some amplifier or some system choices and not from other ...

My own power conditioner for example is not so useful with the Sansui alpha , it degrade the sound but is useful for my other low cost system , it improve the sound ...

For some higher cost power conditioner or power cable , i partake the opinion of carlbads2 as i already said , they can make a difference or not , it is system dependant as he explained well above ...

Now this thread for sure will degrade in a battle between subjectivist who knows quality exist for the ears as a subjective experience of the gear and those objectivist who claim they dont exist if it is not measurable electrically with tools ... The ears being for them an illusionist not a real tool...

I am neither a subjectivist nor a subjectivist ... Then i dont refute subjectivist claims about the power cord because i know by my ears that it is possible to affect the sound positively or not at all with a power cord ...

In the same way, i know as objectivist claim , that the quality of the design is not merely only grounded in human subjective taste , but as they claim must be grounded on some electrical measures as such , but certainly it is not always such and it is not always enough as rightfully claim subjectivists, and it is my opinion , they are grounded also in psycho-acoustics measures ...

I am neither a subjectivist nor an objectivist ... Why ? Because i studied, read about sounds and perceptions , and i experimented ...I am not a fetichist of the mere gear or of the mere  electrical tool ...I believe first and last in the correlation between gear and tool and the acoustics context and the brain ...

«Truth dont invoke nor provoke and dont need a scapegoat and cannot be caricatured» Anonymus thinker 🧐