Does Equipment Break In, or Does Our Hearing Adjust?

Agreeing with what other have said here, it is true that for some of us at least it’s our ears that do the vast majority of the breaking in. I’ve bought identical amps new and listened to them both at the start, and judged them to sound identical - equally bad. Then burned one in for a few hundred hours and noticed it sounding dramatically better. Comparing them again at the end of the burn-in I discovered to my delight that they still both sounded the same but dramatically better than they did at the beginning. I’m not going to insist that some people may not notice real equipment changes over time. But it is fascinating that the burn-in almost always seems to improve the sound rather than degrade it. You’d think there’d be occasional components that go the wrong way. Or perhaps reach their peak sound quality mid-way through the burn in but then slide back a little before stabilizing. Also it seems rare for equipment to brighten its sound signature as it breaks in.

One way to know for sure with your sound bar would be to do before and after measurements. The apparent tonality change should readily show up on a frequency response graph if it was actually caused by physical changes in the sound bar’s performance. Or another option is to go buy another one just like it that’s new in the box and see if it sound bright and tinny.

Now that I think about it there are other possibilities besides just burn-in. Some components could conceivably change sound quality for better or worse over time whether used or not. Some could conceivably sound better after a burn in period, but then lose the burn in effect if not used regularly enough so that another burn in period is required. Some could even start to degrade from excess use but then recover if left unused for a period of time. These all sound like nightmare scenarios to me. I’m glad that the changes most equipment go through due to burn-in have negligible effect on my enjoyment of music. My ears are not hyper discerning so there’s a lot of serviceable equipment that seems stable over long periods of time to my perceptions.

BOTH

Yes.

New speaker drivers need to move and the capacitors in their crossovers need to be “charged” My KEF’s were noticeably better sounding after about a week of leaving them playing 24/7 after I got them!

So I also have a pair of Acoustat Model X speakers with the Servo amps on another system and if I don’t fire them up for a while, they sound awful, thin and lifeless, but once the caps are recharged (about 90 minutes) the system sounds fantastic! After that, the system sounds great with only waiting for the tubes to warm up, maybe ten minutes.