[timb5881]

So you have a DAC with headphone output, when do you decide I need an amp? Of course if the volume is not enough you need one, but what else do you use to decide?

 

[TYATYA]

Volume is a critical but not only one reason. You need an amp for matching amp-headphone.
If no-load condition of both amp and hp have rase up impedance around 1000hz, it can make a V shape output pair together.
Bcs they are not flat, it is better if have compensative for each other.
Less is more, shorter sound path is better. But SP1000 drives hd800s can, it is not as good as to use an inexpensive amp like darkvoice (tune changed). It is my experience

 

[Sound Man]

Volume is a critical but not only one reason. You need an amp for matching amp-headphone.
If no-load condition of both amp and hp have rase up impedance around 1000hz, it can make a V shape output pair together.
Bcs they are not flat, it is better if have compensative for each other.
Less is more, shorter sound path is better. But SP1000 drives hd800s can, it is not as good as to use an inexpensive amp like darkvoice (tune changed). It is my experience

Thanks for your answer. I had the very same question as timb5881.