Why do some headphones sound different even if they're the same model

[Naer]

Like, it's as if sometimes they try to make it sound good, other times they don't even try?

My older Koss sportapro sounds a bit better than my newer Koss sportapro. I wonder if this is placebo and they really do sound the same

What is your experience?

 

[biostud]

Technically the drivers could degrade or change behavior over time, but I've never owned two of the same pair of headphones.

 

[Oyeve]

As an avid owner/user of headphones and having 100s of them I can say that the Koss ones can vary in sound quality year to year. They are dirt cheap (but sound excellent for the price) and having at least 3 versions of each they all tend to sound different from each other. But the Koss cans can't be beat for price and sound close enough that it should not be a concern as long as they sound good. The only thing you can check is the ear cushion. I have noticed that the older versions of the Koss porta cans I have, the cushions seem a little denser and will throw off the sound a bit.

My AudioTechnica ATH-M50X's cushions were peeling so I order a third party brand that was denser and had velour instead of vinyl and were much thick and it threw the sound off from the cans. Took some use for be to get realigned with them but they sound great.

Also, speaker burn-in is a myth!