Does Equipment Break In, or Does Our Hearing Adjust?

@mward so if you move them around do you have to wait for them to break in again?

You get used to the sound there is very little "breaking in" after a few seconds to minutes even with speakers.  

Don’t know, didn’t try to move them. Google it. 

IMO, the more I listen to a song, the more I take in.  At first listen, it is a guitar string sound, but after a few more listens, I am picking up the vibration of the string, and a few more, I am focused in on the decay of the string to silence.  Or, I listen past the string and hear the drum brush in the background.  In my life, this is what I think is often referred to or mistaken as equipment break in because the sound, for me, becomes more detailed the more I listen.  Similarly, if I watch a complex movie once, I understand it and enjoy it.  But if I watch it 3 times, I really pick up a lot more of the plot and character nuances.  Clearly not the same thing, but similar.  

I have experienced and struggled with break-in of audio components for fifty years. It is a pain in the butt… especially when upgrading. Typically high quality components take 600 hours… although the largest portion is done by ~ 200 hours. Typically I don’t hear much change in wires beyond 200 hours, but if I move them in a big way or take them out for a long time and they will need ten or twenty hours to settle down.

All this is completely reproducible and easy to detect for the experienced listener.

I had the experience of breaking in three identical Audio Research Reference 160s amplifiers. I was absolutely amazed at how each followed exactly the same very complicated change in sound. In particular in the 120 hour range after the amps sounded better than at the start, would suddenly sound terrible for a session, then great, then terrible. This flip flop lasted for around 20 hours.

The mind becomes more sensitive to a component at the beginning as you subconscious becomes aware of the sound characteristics. It does’t perceive the sound differently, it becomes able to sense deeper into the nuance.

The Audio Research Reference 5SE preamp required about ten minutes of actual music playing through it each time before it sounded right, even if it had been warmed up for an hour. I thought there was something was wrong with my head. It was absolutely repeatable. I went to a audiophile forum where all the users own high end audio systems (Audio Afficianado) only to find a number of users discussing this peculiarity. The newer Audio Research Reference 6SE does not do this. In fact it needs little warm up to sound perfect.

Anyway, for the experienced audiophile these changes are easy to hear and must be taken into account when creating, upgrading or changing your system. There is no controversy on this subject among audiophiles.