I don't think you quite understood what I meant by that, as it's not even something you achieve for the most part. It's mainly something you get straight off the bat and something that is often not good because what it usually is is gimmicks to hook you in with certain boosts in EQ and such.
You may find this article about break-in very interesting - it's extremely well presented and researched. It's also based on measurements.
If you get time to read the whole thing, it's quite enlightening. Tyll did a batch of tests that basically came up inconclusive. There may be a small physical change going on - but you'd get more sonic change from the condition of pads, or the slight movement of the cans on your head. And these are a member of the AKG family that some claim need major burn-in.
FWIW I did notice change over time with my DT880s. But I also know that it's most likely just my brain slowly getting used to them. Same with my 325is. When I first got them, they seemed really bright. They still do in the first 3-4 minutes putting them on. But after 5 minutes or so my brain adjusts and the brightness fades to a nice comfort level.
My advice is to forget about break-in. Break your cans in naturally - by listening to them. If they change over time, I'd say it's more likely to be your own wonderful internal processor burning in - rather than the physical transducer your wearing.
Hmm... Interesting. I will definitely look into it. As a matter of fact, I was just looking for this kind of info and before I really got into it, you've provided me with at the very least a good start. Thanks.
In regards to the pads and the movement of the cans on my head, believe me I've experienced that. It makes quite significant differences often and I try to calculate that as much as I can when trying to do an objective test.
Like I mentioned earlier, your internal processor burning in is a different factor. It's very easy to test simply by having a large array of the same headphones (which I've had) and comparing them new and "burned in". I didn't very accurately test it because it was driving me nuts (tbh) and it was before I knew about the potential differences in the pads making changes. After experimenting and learning that, I was too crazy at that point so it's safe to say the test was inconclusive. That's annoying, lol... I'll likely be trying it again some time. One PROBLEM I did notice is that over time, the volume of the HM5's seems to be diminishing... That sounds bad to me. It seems like I slowly need to push the volume a bit further for similar things as time goes on. I wish I had one of those testing heads.
And BTW, would you say the same thing about speakers as you do headphones? In theory its very similar so I would guess so. Burn-in is just too logical and in cases too apparent for it to be a myth as it seems likely that you see it. For instance, this video isn't exclusively on that but it's mentioned; take a look at this: http://www.youtube.com/watch?v=OHWP6Bq8rHw&list=FLTNobbLgf2qT-eYV3TF7xmQ&index=47&feature=plpp_video
I know, that's very different, but that's just the video I recently viewed which I remembered hearing it in such a direct way. I'm sure the same principle applies for any other things alike. Another thing that might give me a bit of a perspective on your personal opinion: do you believe in LCD screens burning in/changing over time?
Oops - sorry - just realised I posted the first trials Tyll did - in 2011.
Here's the later article I was supposed to post ........ http://www.innerfidelity.com/content/measurement-and-audibility-headphone-break from Jan 2012.
Anyway - both of them are a good read.
Edited by Typhoon859 - 6/12/12 at 10:20pm