As I have already said, the current set of measurements, highly informative and carefully consistent are great. But there if more to what we, can hear than is described by this limited set. I have offered several suggestions on what they may be. Can you explain when what you hear, is totally in conflict with the expectations? How do you explain another person who has no idea what you changed, care what it costs, or how much effort you put into it without being asked can offer the exact same description of the sound and blame it on sighted bias?
The scientific method is to make an observation, then investigate, hypothesize, test, and develop theory on which we can base a conclusion. Claiming I can't actually hear a difference and declaring the limited set of measurements perfect is making the conclusion first. Completely against the scientific method. How is this not clear enough?
I can't tell you how many times I have labored and spent money tweaking a speaker system having great expectations , brought it in and it stunk. Stunk to me, stunk to my wife. Sighted placebo?
I was stoked. The D30pro measurements were so good, they are hard to imagine in a consumer product. With great expectations, the "glare" difference to my other DAC was barely noticeable through speakers. Differences in very low level detail with headphones I can explain by the much lower noise floor. Objective measure described a difference is sound. Conclusion? Not that much different, good as it gets. Threshold reached and all that.
As I needed another DAC anyway, I wanted to get the Modius but it is out of stock, so I bought the Atom. After all, the conclusion was that is as good as it gets, and it measured better than my Asgard, it should be the same. Tossed it on. Huge difference in the specific sound that bothers me and my wife. I mean walk by the hall different. Sent the Topping back. I really wanted it to work. I mean, it was slick, every feature imaginable, fantastic specs. Loved the remote which surprised me. But the JDS flat out sounds better. So the CORRECT question, is what is different? Can we measure it? Can we quantify it, put it on a scale? Because we measure something as better by belief smaller or bigger must be better, is that true? What does our brain do to sounds based on the pattering it makes when we walk into a room and it evaluated the environment, audibly and visually? What allows us to perceive "Goldilocks"
I am not ready to declare I know everything, we can shut down research, fire all the scientists, kill the patent office because what we know is perfect. If you do, fine, you need not be in the discussion anyway as you have nothing to contribute or take away. Sorry. I hope to not quit learning until my last breath.
FWIW, I had 4 line level preamps and I couldn't tell them apart. My conclusion is we can make them "good enough" I only needed one, so with some romantic attachment overcome, sold my Nak. Not hard on the Hafler or DIY. The Nak was just sweet to use. Massive personal attachment and bias. It did not fit on the shelf, no headphones and I do the EQ in the host.
Dumping the horrible sounding Parasound, I compared my old Creek to my own MOSFET amp. At low levels, I could not tell them apart. By about relaxed levels, they were different slightly. "Signature" as the subjectivists would say. I suggest is the difference in Beta droop between bi-polar and MOSFET. Something we CAN measure. Handles dynamics slightly differently. Neither wrong in any sense. Both just fine. At higher levels, the Creek ran out of power. Quite expected. 40W clipping into my not very efficient monitors. Power supply less than 1/4 the current from my MOSFET that clips close to 100W which has 8 times the rail storage. Curious, the "defect" in the Parasound was not much unlike the defects I heard in DACs. Not exact, but in that range. That confirms there is something that can be measured there.
One last thing:
Probably 2/3s of my CDs sound identical on all my amps, and all my DACs. Source material matters. For example, all my Billy Joel highlight the issue in the cymbals. Joni Mitchel can kill it. Harry James trumpet gets too rough, Buddy Rich is too rough because that is how he conducted his band. Bream plays Alverez, bass strings sound metallic on the Parasound amps. These things are clear enough I can take a CD to stores and hear the same things repeatedly. I repeat ad-nauseum. Amazing how many very prestigious amps failed the Julian Bream test. Equally, last road trip, three integrated amps and I could not hear any difference in the strings. All passed. All "good enough" There is something to measure here.