[goldwerger]

Does anybody know if there is any problem if I plug in 2 different impedance headphones at the same time?

there shouldn't be a problem, safety wise

when plugging multiple headphoens you will hear volume going down, as same power is used to drive multiple loads (true to prettty much all amps that have multiple ports; unless the amps are genuinely separate for them which is rare).

I do wonder though, technically, what happens to damping when that happens - i.e. whether the output impedance shared across two loads of varying impedances results in any kind of averaging which impacts the damping of each of those, or not at all (i.e. parallel driving without any feedback happening). This question is beyond my knowledge as I am not an electrical engineer - if someone knows and can chime in, would be grateul to learn myself..

meantime, try and find out how it sounds..

 

[carboncopy]

there shouldn't be a problem, safety wise

when plugging multiple headphoens you will hear volume going down, as same power is used to drive multiple loads (true to prettty much all amps that have multiple ports; unless the amps are genuinely separate for them which is rare).

I do wonder though, technically, what happens to damping when that happens - i.e. whether the output impedance shared across two loads of varying impedances results in any kind of averaging which impacts the damping of each of those, or not at all (i.e. parallel driving without any feedback happening). This question is beyond my knowledge as I am not an electrical engineer - if someone knows and can chime in, would be grateul to learn myself..

meantime, try and find out how it sounds..

It is essentially how you wrote. If you connect to 300 Ohms headphones to the amp (assuming it is a parallel connection, which is usually the case), then the sum sinks to 150 Ohm. This then has influence to the damping factor of course.

The complexity of the thing is, that headphones represent an impedance (as every voice coil), not just a resistance. So it has inductivity and capacitance too. These three parameters (resistance, inductivity and capacitance) are the so called impedance. Now, two from these three (capacitance and inductivity) are frequency dependent, meaning they represent different values at different frequencies. And two different voice coils/membrans (say a biocelluid and the BE coadted Verité drivers) has different propertiers accros the frequency. So paralleling them can result some alligment/disalligment situations accross the frequency range.

As for how strong these effects are and whether they are observably for the listener is case-to-case different. But manufacturers know how an impedance curve of a headphone runs and they are part of the voicing. So, mixing together two such curves is always a deviation.

 

[goldwerger]

It is essentially how you wrote. If you connect to 300 Ohms headphones to the amp (assuming it is a parallel connection, which is usually the case), then the sum sinks to 150 Ohm. This then has influence to the damping factor of course.

The complexity of the thing is, that headphones represent an impedance (as every voice coil), not just a resistance. So it has inductivity and capacitance too. These three parameters (resistance, inductivity and capacitance) are the so called impedance. Now, two from these three (capacitance and inductivity) are frequency dependent, meaning they represent different values at different frequencies. And two different voice coils/membrans (say a biocelluid and the BE coadted Verité drivers) has different propertiers accros the frequency. So paralleling them can result some alligment/disalligment situations accross the frequency range.

As for how strong these effects are and whether they are observably for the listener is case-to-case different. But manufacturers know how an impedance curve of a headphone runs and they are part of the voicing. So, mixing together two such curves is always a deviation.

Makes perfect sense! Thanks for the more cogent explanation..!!