[carbondream]

There are too many variables to ever definitively determine that there is an audible difference across the board.  Some ears will perceive differences, some will not.  Some drivers will audibly sound different, some will not.  The point is...  until someone buys two pairs of every headphone on the market and meticulously test them in a scientifically controlled environment, the "Audibility Argument" on this topic will go on forever.
That said....
From a mechanical and engineering standpoint... it is RECOMMENDED that ALL moving parts go through a period of "break-in".  Size of the parts or degree of motion does not matter!  The process is to condition and stabilize the moving parts.  To put it generically.... its so those moving things can get use to doing what they are going to be doing for the rest of their lives and its solely for longevity purposes.  For the same reason that you change the oil in your car regularly.  Sure, you dont have to ever change it, and it will seemingly run fine for a while, but we all know how that story will end.  Its the same principle, just on a smaller scale and obviously never changing your oil is going to have a larger impact, quicker, but hopefully you get the point.
So, in terms of "proper care" of moving parts... i would personally suggest a break in period EVERYTIME but you should NEVER expect to hear a difference.  If you do, good for you, but just remember that is not the goal or purpose of a mechanical break-in.
 
Please excuse my lack of head-fi experience.  I feel like this had to have been mentioned by someone else at some point.
If not, i hope it helps.

 

[bigshot]

The difference between two sets of the same headphone is probably greater than any burn in. It seems to me that if burn in was a serious issue, the people who do response charts on cans would publish two sets of graphs- before and after burn in.

 

[blades]

  The difference between two sets of the same headphone is probably greater than any burn in. It seems to me that if burn in was a serious issue, the people who do response charts on cans would publish two sets of graphs- before and after burn in.

 
It is a curious audiophile phenomenon driven by hearing bias.  I've never tested headphones but I once had a chance to do some tests on two pairs of speakers which were known to require a long "break in" period.  A dealer friend was unboxing a new pair of B&W 801 Matrix speakers for testing and delivery.  I asked him if we could do a blind comparison with his floor models which had been in place for several months.  To make a long story short, nobody could tell one pair from the other in a bias controlled test which speaks well for B&Ws quality control.
 
It is true that there is a short period of time in which components in the speaker system experience electrical changes but there is no real evidence that those changes are audible.
 
Most of us who have been involved in bias controlled testing conclude that it is the listener that breaks into the gear rather than vice versa.  A change in sound will be uncomfortable for a listener and will become more and more comfortable as he becomes accustomed to the new sound.
 
Manufacturers, dealers and audio writers push the break in concept primarily to reduce returns.  They know that an audiophile will like a sonic presentation better as time goes on because of this psychological effect.  Actually, I'm going through that right now.  I installed a new Class T amp for my personal computer.  The darned thing as a bass boost and I still haven't adjusted to it.  I've adjusted my subwoofer and still feel like things are a little dark.  I wish the manufacturers would warn folks when they design a bass boost into an amplifier.  In time I'll get used to it.

 

[ab initio]

 Actually, I'm going through that right now.  I installed a new Class T amp for my personal computer.  The darned thing as a bass boost and I still haven't adjusted to it.  I've adjusted my subwoofer and still feel like things are a little dark.  I wish the manufacturers would warn folks when they design a bass boost into an amplifier.  In time I'll get used to it.

 
If I were you, I'd be sending that amp straight back to the dealer. Built-in sound coloration? No thank you. That is one of my biggest pet-peeves!
 
At one point before I was really focused on sound quality, I needed to get some speakers for my desktop at home. I went to Walmart and picked out a set of multimedia Sony speakers with a little (like 5 inch or something) subwoofer and two 2" satellites. The system had nothing but a volume control, so there was no way to balance the "sub" with the tiny little speakers. The thing sounded terrible! The "low end" was handled by the sub, and i think it was basically a muddy-mess from 300 Hz down to 60 Hz and nothing really below that, and then completely underpowered speakers that were nasally if you could actually hear anything over the muddy subwoofer mess. I think these speakers were colored for explosions in games and the beats in pop music because all they could do was make a muddy boom-boom sound. I spent the next 4 years almost exclusively listening to headphones.
 
Colored equipment? send it back, it's not worth your money if you can get something better at the same price point!
 
Cheers

 

[bigshot]

It might even be a sign of a manufacturing defect. I second the suggestion to return it while you can.

 

[blades]

I tend to agree with you both but the boost isn't all that bad after adjusting my sub and, when I get a chance, I'll EQ the computer to cut the bass a little.  The amp cost $66 and change.  I'm not sure what should expect for that.  I think it's fixable.

 

[bigshot]

Well, I guess if it is a manufacturing error and it burns out eventually, it's no great loss. It would be nice if that imbalance was consistent over time though and not drift. A friend of mine had an equalizer that you could set one day and two days later you would have to set it all over again.

 

[blades]

I spent about 5 minutes with the Windows equalizer and straightened it out.  The amp sounds accurate now.

 

[ab initio]

  I spent about 5 minutes with the Windows equalizer and straightened it out.  The amp sounds accurate now.

 
We need a way to quantify how well equipment responds to equalization/correction. My opinion is that all devices that behave linearly, even with EQ, are equivalently "accurate." Namely, if they can be configured to output the original signal over a reasonable range gains with inaudible noise, then it is effectively a "perfect" component.
 
THD+N is part of it, however, depending on what the original frequency response is, if adding the required equalization to achieve perfect response results in audible distortion, then the component fails to be considered accurate. However, any component that response linearly to the input is equally capable of high-fidelity reproduction.
 
Thoughts?
 
Cheers

 

[SilverEars]

Anybody have studies done on EQ?  Like different aspects of the headphones measured after EQ so that any patterns can be noticed.  

 

[bigshot]

If a headphone can reproduce all frequencies at a high volume cleanly, it can be EQed. Of course massive corrections are out of the question, but if a headphone can reproduce a wide spectrum of frequencies, it's probably starting from a place not too far from flat.

 

[blades]

   
We need a way to quantify how well equipment responds to equalization/correction. My opinion is that all devices that behave linearly, even with EQ, are equivalently "accurate." Namely, if they can be configured to output the original signal over a reasonable range gains with inaudible noise, then it is effectively a "perfect" component.
 
THD+N is part of it, however, depending on what the original frequency response is, if adding the required equalization to achieve perfect response results in audible distortion, then the component fails to be considered accurate. However, any component that response linearly to the input is equally capable of high-fidelity reproduction.
 
Thoughts?
 
Cheers

 
The problem with my post is that I said the amp now sounds accurate.  I should have said it sounds the way I want it to sound.  Accuracy can't be heard.  It can be measured.  Anybody who fools with the frequency response without measurements is fiddling, not equalizing.  So I fiddled with frequency response to make the system sound more like it did before I changed to the new amp.  I corrected what I perceived as a slight bass boost.
 
While any variation from a flat frequency response can be referred to as distortion, that isn't what we mean when we refer to the term.  Normally we refer to IM or harmonic distortion.  While the EQ does produce audible differences in frequency response it doesn't necessarily produce audible distortion.

 

[bigshot]

  Accuracy can't be heard.  It can be measured.  Anybody who fools with the frequency response without measurements is fiddling, not equalizing.

 
That isn't necessarily true. When I first set up my system in my new house, my sound engineer friend was busy working on a project and couldn't come by for a couple of months,. So t equalized my system by ear using wide frequency recordings of acoustic instruments that I knew to be flat. It took a LONG time, but when I was done, my buddy was free again, and he came by with his signal generator to fine tune it for me. He spent about 15 minutes running back and forth through the range and told me that he could hear a few narrow dips and bumps, but I had gotten it as close as I could have using a 5 band parametric. He said I had gotten it to the point of what would be his first pass. If he was EQing it for studio work, he'd go back and iron out the details, but for that he'd need an equalizer with more channels. It was good to hear that, because I was very happy with my curve.

 

[blades]

You get the golden ears award.

 

[castleofargh]

 It was good to hear that, because I was very happy with my curve.

I'm sure you have great curves.