[stalepie]

like a DSP plugin for Foobar. Perhaps a strange request.. 

 

[MindsMirror]

You could use an EQ to simulate the altered frequency response. You would need to know the shape of the impedance curve first in order to do that.

You can wire a couple of resistor's between your amp and headphone which is effectively the same as adding output impedance.

 

[zareliman]

  like a DSP plugin for Foobar. Perhaps a strange request.. 

There's impedance adaptors for your headphones. That's the closest I know. The other solution would be to dampen the frequency response peaks through an IRS.

 

[castleofargh]

no, you can't really hope to simulate all the behaviors of changing impedance. you could EQ whatever might risk to change(like on multi BA IEMs) but only by calculating it yourself, and maybe simulate another impulse responses for more than just an EQ impact, but that might not be enough to compensate the physical impacts of changing the circuit for real.
 
physical modifications:
to increase the impedance of the amp you can find little adapters with a pair of resistors(one for each channel) in series that you put between the amp and your headphone.
to try and decrease the impedance of the amp you can go with a voltage divider.
 
both solutions are wasting energy so you need to be sure you'll still have enough power from the amp. aside from experimenting, those have usually some detrimental impacts, the only time where you would use those is when you really know what you're doing and the downside is clearly compensated by whatever you're correcting(struggling amp into too low an impedance for its own specs, IEMs with garbage signature into a high impedance amp, or hissy amp into sensitive IEM).

 

[fredeb]

  no, you can't really hope to simulate all the behaviors of changing impedance. you could EQ whatever might risk to change(like on multi BA IEMs) but only by calculating it yourself, and maybe simulate another impulse responses for more than just an EQ impact, but that might not be enough to compensate the physical impacts of changing the circuit for real.
 
physical modifications:
to increase the impedance of the amp you can find little adapters with a pair of resistors(one for each channel) in series that you put between the amp and your headphone.
to try and decrease the impedance of the amp you can go with a voltage divider.
 
both solutions are wasting energy so you need to be sure you'll still have enough power from the amp. aside from experimenting, those have usually some detrimental impacts, the only time where you would use those is when you really know what you're doing and the downside is clearly compensated by whatever you're correcting(struggling amp into too low an impedance for its own specs, IEMs with garbage signature into a high impedance amp, or hissy amp into sensitive IEM).

Do you think one could measure the output impedance of the amp , take that value , and take similar value resistor  and put that in parallel with the output , thereby halving the output impedance of the amp ? 
 
Here's some interesting reading :
 
http://nwavguy.blogspot.co.za/2011/02/headphone-amp-impedance.html

 

[castleofargh]

among other topics, you get some practical examples and some of the drawbacks pretty well explained here http://www.head-fi.org/t/627111/what-is-the-sound-quality-of-iphone-ipad-ipod-touch/195
 
it's a multiparameter problem: ending up with enough power, not showing too much of an impedance to the IEM(if that was a problem), attenuating the signal enough to remove background hiss(if that was the problem), and not showing too low an impedance to the amp itself. with the loss of efficiency, the amp will usually be pushed even further which means using both more current because of the small load and more voltage to compensate for the attenuation, sometimes resulting in distortions or clipping for asking too much.
so it can be hard to satisfy all the desired parameters at once. 

 

[MindsMirror]

  Do you think one could measure the output impedance of the amp , take that value , and take similar value resistor  and put that in parallel with the output , thereby halving the output impedance of the amp ? 
 
Here's some interesting reading :
 
http://nwavguy.blogspot.co.za/2011/02/headphone-amp-impedance.html

No. The output impedance is internal to the amp, you don't have access externally to be able to put a resistor in parallel with it. You can only put a resistor in series with the amp output, increasing the effective output impedance seen by the headphone, or in parallel with the amp output/parallel with your headphone (they are equivalent), decreasing the effective load impedance and exaggerating the effect of the amp's output impedance.
 
If your amp has a resistor in its output you could modify it internally by shorting it with another resistor, but that's a bad idea. The resistor is there for a reason, lowering it's value could cause the amp to become unstable.

 

[fredeb]

  No. The output impedance is internal to the amp, you don't have access externally to be able to put a resistor in parallel with it. You can only put a resistor in series with the amp output, increasing the effective output impedance seen by the headphone, or in parallel with the amp output/parallel with your headphone (they are equivalent), decreasing the effective load impedance and exaggerating the effect of the amp's output impedance.
 
If your amp has a resistor in its output you could modify it internally by shorting it with another resistor, but that's a bad idea. The resistor is there for a reason, lowering it's value could cause the amp to become unstable.

So I guess that in this case one should match amp to 'phones from scratch .