Sword, appreciate the answer. Yes, I do disagree and you're welcome to disagree with me too. I have no motivation to try to convince anyone of any conclusion other than gather more information for myself. Prior to me playing with op amp swapping, I'd already read the opinions of those who say it makes no difference and those who said otherwise.\n\nIt's because of that, I bought several amps and many different op-amps to test it out for myself. I can distinctly tell differences in sound stage between op amps, I can distinctly tell differences clarity and other characteristics.\n\nFor low budget IC amps, yes, for the most part they are neutral, and hard to distinguish between one another. For that reason I would not bother. When you get into discrete op amps or different higher priced ones, you can distinguish between clarity in leading edges, sound stage characteristics as well as others. Some of those sound characteristics can be explained by FR charts, but not everything.\n\nWhether you agree or not, if an end user perceives a difference, and that difference is worth the expense, then that's their prerogative. No one said that you have to agree or do the same. If you don't hear it, then it's not worth it. My mother could care less if she listened to a song on a crappy phone speaker, than through a high end system. Not worth it for her.\n\nRegardless of what type of listening test you do, we're talking about perceivable differences from the human ear. In this way, it's never going to be perfect - so trying to "science it" is not very productive in my opinion.\n\nWe all have different hearing ability. It also matters how "trained" your ears are. I'm not saying you need golden ears, but someone who is not trained to look for certain attributes may not notice them.\n\nEven if you show the same painting of a house to 2 different people who have 20-20 vision and ask them to describe what they see, you may get different responses. They both may say a house. The person who has trained to analyze artwork may tell you much more - like the the name of the artist, based on the color palette used, or the style of brush strokes, etc. A noob would not make any of those inferences even though they are looking at the same image unless they were taught to do so.\n\nAgain, I don't care to convince anyone here, this if for my own peace of mind. Thus far I have not heard any convincing, logical, scientific arguments for what I am hearing - other than I am audio fool and this opamp swapping is BS. Very dismissive.\n\nIt's a complete logical fallacy to say if YOU can't measure it, then it's just subjective and it does not exist. It could mean (but not necessarily) that you just haven't discovered the right testing method to measure that characteristic. It could mean that existing testing methods are incomplete.\n\nThink 3 blind men and an elephant.\n\nI've yet to see a spec sheet of an op-amp show a "measurement" of a sound stage, but from my personal experience and it seems many others, they can discern a difference between the soundstages of op amps, clearly and consistently.\n\nAre we all just fools? Or is it just easier to name call when we can't explain what does not fit into our own cognitive bias limit of knowledge.\n\n\nHe did tell you about how to do listening tests to check that you actually can hear a difference.