Nearly all manufacturers do not advertise/exhibit their product measurements? Why?

As to tweaks, I say try it and if you like the sound results, keep it. Otherwise, return it. I tried many footers when a dealer continued to send them to me to evaluate. One was terrible under all equipment and about 8 others were more similar than different in effect.  None were inexpensive, ranging from $49 to $500 per footer, a broad range but cost more than most footers were in the 1980s (cones, silicone rings, springs, etc).  I think roller balls in captive devices were the next step, vibraplanes and then multi-density/elastomer type devices, almost all more expensive. 

It wasn't until I purchased the Townshend Seismic Sink that I decided to keep my VPI TNT VI in 2006.  It has terrible vibration isolation, much worse than the rubber block and spring footers of my VPI 19-4.  That Townshend is fantastic for turntable isolation (my equipment rack was not the problem, made of welded steel tubing filled with 50/50 shot and sand/dead sounding when struck).  
 

"The industry is transforming though because if they don’t measure, then I might. :)"

What unbelievable arrogance. No wonder people in the industry regard your site as a joke. You still have not answered if you actually ever check whether Yang sends you off the shelf products or cherry picked ones. This is now the fourth time I have put this to you. Scared? If you do check, show us scientific evidence that you do, else it is just your statement. Perhaps make a video showing an independent person check as you open an off the shelf product and one sent to you.
 

Yes, go ahead and measure my Synergistic Research Atmosphere X Euphoria SPDIF digital cable.  I would pay $25 to find out how it measures.  But I'm not sending it to you, you'll have to acquire one on loan from a retailer, SR or someone else using it and I will pay for the results. 

@holmz You are correct. He could have needed better fuses or IC cables or something else.

The question was:

1. how did you know it needed the power cord?
2. What is happening with the power cord that makes it better?
3. Is there a way to measure it?
4. or does it not manifest itself in a measurement?

However, several other friends tried the Pangea power cable. No go. They disliked it compared to whatever they had been using. I know how great my power cables sound on several systems and the lack of returns on 1000s sold privately. So, I lent him the less expensive, earlier model, just one and he was dumbfounded. He replaced all the power cables. He was ecstatically happy. I’m happy for him and after he also changed his pre-amp input tubes, I am happy to listen to his audio system.

Good for him.

Yes, I’m only telling fables in your opinion. Not! You can believe it’s just another story and the sound could be the same. Not!

Let me rePhrase it.

“How can I tell the difference between your story and a fable?”
How would I know whether it is true and a real thing or a psychological thing, or even just a story.

I’ve related how poorly his system reproduced low frequencies with very jagged sound and now a smooth sound up and down the scale.

OK- Is there a plot like @kota1 showed where the frequency response went from jagged to smooth?

Voices are full and forward (instead of floating in the rear and thin sounding). I was using my CDs which I am very familiar with. If that earlier system from 2019 were mine after spending nearly $1/2 million, I also would have been very disappointed. It may not be perfect but after a few changes (10X more expensive power cables, 5X less expensive input tubes) his now high end sounding system is one I would be proud to own (except it is only CD based, uploaded to a computer and thumbdrives, going through a computer directory, through a Berkeley USB something or other to the DAC, then pre-amp then tri-amped multi-box speaker system). Too much work for me, I just plop the CD into the transport (or work a little more with LPs, 78s and R2R).

@td_dayton 

also updating to point out that this guy, while he's been quite critical of some of the reviewers i enjoy reading like lavorgna, doesn't appear to have a history of attacking other measurement-focused reviewers and booting them from his comments section. food for thought

Yes, Archimago appears to be a well-adjusted human. Also a decently articulate writer. I should check his blog more often.