Larsman, I have indicated several times what is happening in all instances of break in. What do you think I would say about your headphone occurrence? You, as well as everyone else, it seems, have never done direct comparison of two identical products, one broken in and the other new. If anyone has, please correct me, because I do not wish to paint the group with a broad brush - unless it applies!
Thus, the answer according to everything I have said is clear, that if you had two pair of the same headphones, broke in one pair and then compared it to the new one, you would hear no change. I wish to stress that I have no intent to call people liars; perception is perception. I believe that your electronics are more consistent than your hearing. As regards that conclusion, I seem to be the only one here who can say that, based on actual comparison of multiple products all broken in used in a system compared to the identical system of new products.
As I said before, any account of, "I heard it change over time,' is fundamentally weak evidence. It pales in comparison to having two systems of multiple components, one treated and the other new, directly compared. If anyone wants to hold a contrary opinion, you do so against the weight of the stronger evidence.
samureyex, you are correct when you said, "If it sounds slightly bright, or dark, or sassy, insert any of ht words It will forever have that problem." Yes, because break in does not audibly change the sound of a product. In my testing, break in did not change the sound at all, which a logical person would accept as a possibility. It is irrational to preclude the possibility that the listener's perception could not be the cause of thinking the equipment is changing.
melodic, your comment, "l think if people want to hear a difference, they may well listen in more detail and think they are hearing things they never noticed before. Our Hi-Fi systems are invariably courtesans, which hoodwink us into believing, what we want to believe," is well said. Habituation is a key part of the belief that the equipment is changing. As more is heard, more mental data points are made, we fool ourselves into thinking that the sound is changing.
i also tested tubes and warm up. No difference when comparing broken in and warmed up gear versus identical product new and cold start.
This is no minor issue; the entire industry is predicated upon a misnomer that the equipment undergoes audible changes over time. That's a problem that needs to be addressed because it negatively influences how people build their audio system.
There are many things in this hobby that are commonly done that do not pass the Law of Efficacy and are not worth believing or doing. In contrast, there are things not commonly done that would greatly enhance system building. Anyone who has experienced frustration getting the system to sound as they wish should read my book.
