@amir_asr Here is the problem: there is no proof point that the assertion of said designer is true. You say he did "extensive listening tests." I guarantee that you have no idea what that testing was let alone that it was extensive. What music was used? What power level? What speakers? How many listeners? What is the qualifications of the designer when it comes to hearing impairments?
Story is told and believed. Maybe it is true. Maybe it is not. After all, if he saw a significant measurement error, logic says the odds of it sounding good is low. After all, why else would you tell that story? If the odds are low, then we better have a documented, controlled test that shows that. Not just something told.
Exactly. I believed something "told" once. Thought I’d put it to the test myself. It was about a really great measuring DAC on said forum. All looked good on measurements and graphs. I took the plunge, went out and bought it with intent it would be a long term keeper DAC. Played it for just under two weeks. Unfortunately, ended up sending it back for a full refund and kept a different unit that measured worse. This other worse measuring unit sounded so much better and was notably more engaging to my ears - for half the price. My ears, my preference, is #1. Summary, what measured better did not sound better. End of story for me. And, preference can vary from one person to the next, no matter what the graph wants to show.
Thanks to those in business who understand this and offer a helpful refund policy. Not everyone is going to like the sound of their designs.