Wow, you just stated that all modern op amps are perfect. Yes, you did not state that all opamps made since the beginning of time were perfect (yes, I did not quote you correctly). What you stated before was just what you said: "all modern opamps".....you probably mean after 1980?....I quess that is when you stopped listening. All "modern" op amps have a sound and it is not confimation bias or a bad design flaw. This is where thousands of people (including world class designers) disagree with you. They know that certain brands of op amp sound differently (and most believe discrete op amps are the most transparent). But you have to listen to know.....something you do not do (at least with op amps).
The changes I do to class D amps lower the perceived noise. You hear farther into the recording.....more decay, more ambience, better imaging, more correct harmonic structure, more transparent and real......this is REAL noise reduction.....not some number on a graph. I do no know more about basic design than most designers, however I have more practical knowledge of implementaion and parts and how they affect the sound than most designers. I have been doing listening tests since the mid 70s....and was the first person (back in the late 70s), that I know of, that did straight wire bypass tests on wire....yes, no wire was perfect....
The companies that usually make the best sound do both....they design and they tweak like crazy. That is why they keep updating their stuff.....like the guy at AGD. Check out this page on Burson Audio. Go to the bottom of the page and see all the pics of customers products that were upgraded using their op amps.....you can keep loading more and more and more of them. These people have circuits that are flawed and they have expectation bias?.....come on......This is just the tip of the iceberg worldwide. At the top of the page are Utube reviews of the op amps. You can keep making stuff up and believing it and telling the world about it.......but it is not truth unless it passes the listenng tests. The people who have listened do not agree with you. Burson is now in their 7th generation of discrete op amp....they never stop tweaking....for they know there is no perfection. it is a goal. When you get to the top of the mountain......you look for higher mountains to climb......same with our soul. Love is infinite......the more you eat....the more hungry you become. It is the ULTIMATE ADDICTION.....bringing the highest joy......for everyone.