I know where you're coming from and what you believe. I once thought along those lines too. Then back in about 2002 Dave Elledge showed up at my shop with some power cables that he swapped into my system and it changed everything.
I know all about the old placebo effects, physiological expectations, ABX comparisons, etc. I am even certified as a hypnotist.
All of that aside, if you can hear the difference between a early 80's cassette player and the latest digital gear or vinyl then you can hear the differences in a USB cable swap in my system. It won't matter what your expectations are. And if you can't hear the difference in those devices then you have no business being in this hobby.
And the measurement only engineers typically can't even tell me why all the different digital playback software's sound different. I have iTunes, Pure Music, Amarra, Audirvana, and SB Play. They only send out 1's and 0's right? But they all sound different.
Imagine if all we did was measure a system and not listen to it. Who needs music right? And whatever speaker measures the best will sound the best right? I can make two speakers measure exactly the same but sound very different.
Come down to Lone Star Audio Fest next month and we'll open those ears to a new reality.
"They only send out 1's and 0's right? But they all sound different." -- No they don't, digital links either have errors or not, and typically when there are errors, the audio gets muted for protection against full scale glitching. If you send a Word file over a better USB cable, is the grammar improved?
"I once thought along those lines too." -- Is that to imply that I haven't figured this stuff out yet? This is the kind of pitch cult members use.
"Imagine if all we did was measure a system and not listen to it." -- Why do people even say such things? Of course those who measure ALSO listen.
In fact, designers who do both rigorously and systematically learn the connections between what you measure and what you hear. Those are the best designers. Understanding the science and engineering behind it is required for optimal results. Please don't tell me someone who learned circuits on YouTube (or by putting kits together) is as good of a equipment designer as an EE with both the degree AND the experience!
"some power cables that he swapped into my system and it changed everything" -- If you want to know my thought on power cables, read this:https://audiophilereview.com/audiophile-news/can-power-cords-have-an-effect-on-an-audio-systems-sound.html
I'd like you to understand that I'm all for the truth. Definitive, measurable, reliably provable truth. As for my feelings on music, that's a different thing all together. I listen daily and experience all the emotion other listeners do. I'm also a musician, or at least I play one on TV.