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

Totally agree excellent response. We could do the same with taste and smell. Do we get an analytical report on food before we choose restaurants- No!

I once went to an apple pie contest. The panel of experts, some with 30 years experience in apple networking, took samples of each of the pies, put them in a blender, and then tested each sample for colour, lubricity, light transmission, density, ph, and of course percentage of sugar, fat, carbohydrates and fibre. Their conclusion? Within the experimental errors of the measuring devices they were all the same. The gave the blue ribbon to the cheapest pie. 

My audio engineer feels that it was a current spike that shorted one of my tubes, and so after 55 years I finally caved in and bought a Furman power conditioner from Crutchfield, on sale from $1000 down to $599.

It provides a “current reservoir” of an extra 45 amps for the amplifiers and that has made a big difference with regard to the texture, detail and authority at the bass end.

So that seems a worthwhile investment.

I still use chain-link fence for my cable interconnects.

Grover Huffman Pharoah power cable

Shunyata Taipen around 2010 ,  A small increase in bass, but in every setup  I've used in in , lots of air in highs. Sounds a little unnatural after a little while.