Quote:
The theory is that letting the headphone's drivers "burn-in" with music will let the drivers "loosen-up" similar to how a new pair of shoes will loosen-up from when you first wear it. Having the drivers loosen-up supposedly alters the sound of the headphone a bit, though every once in a while I will see posts that claim there is a pretty large difference in sound. Pink noise is commonly used as a "burn-in" track because it carries all of the frequencies in the sound spectrum within human limits and each octave has the same amount of noise power.
It's a debatable thing and I believe there's a huge discussion for it in the Sound Science forums. I gave the M-100's a try out-of-the-box and wrote down my impressions. I then let it burn-in with pink noise for a whole week, non-stop, at a high volume level (a level I would listen to on a noisy public bus), without listening to any other headphones/earphones, and gave them another listen and I didn't notice anything different. So for me, for the time being (AKG K 701 arriving on Monday, will find out for sure with that headphone since it's infamous for being a headphone that "requires" a lot of burn-in time) burn-in is still a myth.
Tyll at Innerfidelity has a few articles about it as well:
Part 1:
http://www.innerfidelity.com/content/evidence-headphone-break
Part 2:
http://www.innerfidelity.com/content/break-part-deux
Part 3:
http://www.innerfidelity.com/content/measurement-and-audibility-headphone-break
There has to be a reference point in which you compare the "burning in" headphone from time A to time B to time C. So if you keep in reference with another relatively stable headphone, you might actually hear differences.
As for Tyll's findings. They still remain unconclusive. There changes in the midrange of the AKG can be audible (tested using EQ) as they increment by 1 dB over a range. It's still highly debatable though, and all measured data so far has resulted inconclusive regarding driver burn in. We actually don't know what specifically will burn in. Could it be the pads? Remember, any change in the pads can adjust sound, and as pads age, they adhere better to your head leading to a better seal = better overall sound (for the majority of us). Could it be other things? Cable? I'll stop there though, I haven't tested cable burn in, but the theory does make sense, but may not be audible: as cables burn in (copper ones) they will oxidize creating a layer of copper-oxide on the outside. This reduces the radius of copper for electricity to run through and increases resistance.
Increase in resistance can create change in sound.
So even if there is burn in somewhere, we don't know what specifically will burn in. The reason why I burn in? Well, first, I do hear change over time, but
second (as a reviewer), anyone else who believes in it will get mad if you don't burn in, so take the safe road and do it if you're writing a review.