[Atavax]

I recently ordered a Hifiman HE 400 and i currently am using a hot audio bit perfect dac. I am wondering if I would benefit from buying a separate amp, or if the bit perfect dac's built in amp should provide enough juice for the H 400.

 

[davidsh]

If you could throw some specs on the headphone out.. 

 

[Atavax]

Sensitivity: 92.5 DB
Impedance: 35 Ohm
 
anything else relevant?

 

[davidsh]

Was thinking about the headphone output one the DAC. If no information is to be found, you must try to find a fellow owner of the 400/DAC you got.
 
I don't really think that DAC is powerful enough. But I don't know.

 

[Atavax]

Is the impedance the primary indicator of how powerful an amp you want? Like i've been using the bit perfect dac to drive my sennheiser hd 598s which are 50hms impedance. THe HE 400s are 35 ohms, so is it likely that my dac will have an easier time driving the 400s then my current 598s?

 

[davidsh]

Am sorry to tell you that is not so. There are 2 factors: 1 is impedance, the other is sensitivity. The HE-400 has a very low sensitivity and is therefore pretty hard to drive. In contrast, it requires almost 10 times as much power as hd598 to play equally loud, meaning an amp is strongly adviced, though it can sound decent from a computer or phone etc.
 
If you know a bit on math, ohms law and the logarithmic scale I can help you understand in further details.

 

[Atavax]

one more quick question. with a usb dac/amp, do you get any increase in the power if you were to plug the dac into a powered usb hub? Or does it get all the power it can handle through the usb connection with the mobo?

 

[davidsh]

  one more quick question. with a usb dac/amp, do you get any increase in the power if you were to plug the dac into a powered usb hub? Or does it get all the power it can handle through the usb connection with the mobo?

It gets all the power it can handle through usb unless there's a power cord too. If you really want to be certain it gets as much power as possible you can plug it into an usb 3 port, though I doubt it will make any difference in performance.
 
I am not too certain on the exact power requirenments of the HE-400, but half a watt (500 mW) into 32 ohms should be plenty to power them nicely.