Everything matter in the audio chain. Tests prove it!

OP,

Yes this is interesting and potentially of some value in choosing or tuning a system. The more tools the better.

Yes everything matters including the individual. 

If you have a high-end projector in your stereo/video room, try an audiophile power cable. I recently experimented with a SOTA power cable from Audio Magic replacing the stock cable and the improvement in picture quality was dramatic. I guess everything does matter! 

Everything matters even more if it isn't plugged in. Yah, some of my customers were concerned about a unit that I sold many of, not working. To cut to the chase, I quit putting the power button on the rear of the unit just for that reason.

  Of course everything counts, it is just a matter of to what degree. One exception would be that if a cable or component had an issue in the first place and you replace it with something working properly, then no doubt you will hear an improvement. 

 That is a coarse way of stating that everything does matter but to varying degrees.

@teo_audio 

the differences will be notably more huge, if one does transient and complex transients stacked and their harmonics, as a fundamental test.

I take it you must know of tests that have already shown this?