[cuiter23]

  IMO, once you can drive a headphone properly, scaling is just a myth. What feature of another amp will make it scale better?

 
I don't want to start up the HD600 vs HD650 wars again  
 
Innerfidelity tested the nominal impedance of HD600 to be 307ohms and HD650 to be at 320ohms. Although the HD650 does seem to be ever so slightly easier to drive louder with the same amount of power output. For both to bring out the lushness of the vocals, the mids indicate at 500ohms. Not really making a point just listing some facts.
 
As for power, the more power, the cleaner the headphones will drive. Of course, more power the better. 

 

[StanD]

   
I don't want to start up the HD600 vs HD650 wars again  
 
Innerfidelity tested the nominal impedance of HD600 to be 307ohms and HD650 to be at 320ohms. Although the HD650 does seem to be ever so slightly easier to drive louder with the same amount of power output. For both to bring out the lushness of the vocals, the mids indicate at 500ohms. Not really making a point just listing some facts.
 
As for power, the more power, the cleaner the headphones will drive. Of course, more power the better. 

The difference in impedance is small and nothing to be concerned with. Once you have achieved the power required by the DR and headroom, anything above that is not used and will contribute nothing. Get a clean amp with enough power and one is good to go.There are too many myths circulating that unduly influences people, Most headphones need 1W or less, if anyone thinks that they have to spend a ton of moolah to achieve this, go for it, I won't stop anyone. There are few headphones like an HE-6 that need a few watts, other than that it's all anecdotal.

 

[kman1211]

   
I don't want to start up the HD600 vs HD650 wars again  
 
Innerfidelity tested the nominal impedance of HD600 to be 307ohms and HD650 to be at 320ohms. Although the HD650 does seem to be ever so slightly easier to drive louder with the same amount of power output. For both to bring out the lushness of the vocals, the mids indicate at 500ohms. Not really making a point just listing some facts.
 
As for power, the more power, the cleaner the headphones will drive. Of course, more power the better. 

I find my HD 600 and HD 650 pretty much the same in terms of drivability, that's likely impedance variations from one headphone to the next.
 
@StanD
 
I have to respectfully disagree with you there. What you are saying basically implies that higher end gear doesn't make a difference given it can power the headphone properly. The power of the amp can change things without a doubt, higher current and greater voltage swing does impact the sound. The quality and consistency of the power, i.e. the power supply. The various different designs and tunings of amps will also change things. And various other factors I'm likely not even considering. Are the differences sometimes horribly exaggerated? Yes, but there are differences, sometimes quite noticeable.

 

[StanD]

  I find my HD 600 and HD 650 pretty much the same in terms of drivability, that's likely impedance variations from one headphone to the next.
 
@StanD
 
I have to respectfully disagree with you there. What you are saying basically implies that higher end gear doesn't make a difference given it can power the headphone properly. The power of the amp can change things without a doubt, higher current and greater voltage swing does impact the quality. The quality and consistency of the power, i.e. the power supply. The various different designs and tunings of amps will also change things. And various other factors I'm likely not even considering.

Higher voltage swing is required for for higher impedance cans, at the sametime it will require less current. Low impedance cans need the opposite. One does not have both at once without destroying one's headphones. As I said, once you exceed the driving requirements of the cans, any more power contributes nothing. Exceeding the max power capacity of the cans will damage them. Who needs to reach or exceed the threshold of pain or damage their hearing. Once a power supply has regulated sufficiently to make hum/ripple inaudible and to sustain power levels, any more is waste,
There is far too much marketing BS and not enough reality with these products.
The HD650 has a max power of 500mW which when sustained will damage your hearing, when exceeded will destroy your 650's. One needs far less than 500mW to drive HD650's.