Disclaimer: Most of the graphs listed here are animated GIF images.
It is generally known that a new pair of headphones must go through a "warming up(aka break-in)" phase for a certain period of time before it opens up its true sonic potential. Previously, both electroacoustic and psychoacoustic aspects of a 100 hours-long headphone break-in have been presented with SONY MDR-EX1000(electrodynamic microtransducer), Sennheiser HD650(Full-sized electrodynamic), Fostex T50RP(isodynamic), and VSonic VC02(smallest microtransducer) The physical transformation is evident in all cases, yet its degree is not of a night and day difference, as audiophiles normally describe it.
Creative Aurnava Live! 2 is equipped with a pair of Foster's bio-celluclose drivers with a separated surround made of urethane. According to Akihiko Hosaka, the senior manager at Samsung electronics Inc., who developed Samsung YA-EF310,
"The diaphragm of a headphone available in the current market is mostly made out of a polymer film. In this case, since this type of headphone doesn't need a separate damping mechanism (such as a spider / suspension of a loudspeaker) implemented, I am quite certain breaking it in would have no effect at all.
However, manufacturers sometimes utilize a separate damper, which is made out of either rubber/urethane-related materials, to the driver of their high-end models. As this separate damper works, just like with a loudspeaker, above the glass transition temperature, its physical property might change slightly as a result of breaking-in. Should a break-in occur, it must be related to something happening at the resonant frequency."And since Foster's BC driver is made in such way, Mr. Hosaka's statement shall be relevant to the topic more or less.
A brand-new Creative Aurvana Live! 2 is to be broken-in for 100 hours straight with XLO's break-in sample (100 dB SPL @ peak), driven with an Objective 2 headphone amplifier. Once the headphone is placed on HATS, its physical placement must remain untouched for the next 100 hours in order to prevent any placement-related deviations. In addition, in order to eliminate any unwanted effects derived from sources other that the driver itself, a special jig is created so that the cushion is free of mechanical settling during the break-in phase. And the temperature must stay within ±1°C when measurement is carried out. Each 10 times averaged pre break-in & post break-in measurement data are to be compared, and should any type of change occur, they are to be reproduced back utilizing a binaural recording technique to be ABX-compared.
Overall impedance is slightly decreased after the break-in.
While the left driver exhibits increased sensitivity (>1dB) in an even manner throughout the entire frequency spectrum, the right driver shows change mostly in the low-mid frequency range, at which resonances are present.
Again, there is more discernible difference shown on the right driver. The distortion level on the left driver remains largely unchanged even after 100 hours of break-in.
ATTENTION: In order to accurately reproduce these binaural samples, listeners must use a flat diffuse-field equalized headphone, such as Etymotic Research ER-4B or STAX Lambda PRO with ED-1. Otherwise, samples can still be compared relatively, but the accuracy of the reproduced result can not be guaranteed. The reference sample is an excerpt from the free hi-resolution sample provided by 2L - the Nordic sound. It is highly recommended to download below samples for critical listening experience.
Reference sample @ 24-bit / 96 kHz
Brand new Creative Aurvana Live! 2
Post 100 hour broken-in Live! 2
As previously confirmed by others, 1 2 3 4 5 6, and by myself, 1 2 3 , the physical effect of break-in is quite evident. However, it is questionable whether drivers with separate damping mechanism tend to be more affected as suggested by Mr. Hosaka of Samsung Electronics. Moreover, psychoacoustic aspect of Creative Aurvana Live! 2's break-in has been demonstrated for ABX comparison so that listeners could verify the audibility of 100 hours of what-so-called 'warming-up'.