Hey guys,
Just purchased a pair of Hifiman he400se headphones for my desktop they should arrived next week and was wondering if i would need an amp or not my motherboard is a MAG B650 TOMAHAWK WIFI / (MAG B650 TOMAHAWK WIFI). Thanks
They will probably work okay but they do like power
A quick google on the specs shows HE400se comes with a pretty standard (& low) impedance of 25ohm. Your Tomahawk’s sound card should be fine driving it without any issues.
However, if you’ve spent $100 on a nice headphone. You probably want to spend another $100 on an external DAC with headphone amp for music. If only for gaming or AV, then no need to bother. 
Low impedance doesn’t necessarily mean easy to drive, it can also mean that it needs high current, which basic amps can struggle with, just as they can with high impedance headphones which need high voltage. The sensitivity is a better measurement of how easy it will be to drive but even that can be misleading. Generally speaking I would recommend an amp for planar headphones as they tend to want a lot of current.
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Well, easy test is to plug them in and see if the sound is distortion free at the volume you like.
Getting an amplifierand running it from the soundcard (or DAC/Amp Combo unit) is always an option down the line.
To estimate power requirements, you need the headphones impedance and sensitivity (usually given in db per Volt). Since the HE400 is a planar magnetic driver, sensitivity will be quite low (high 80s or 90s maybe?) compared to a dynamic driver headphone (most exceeding 100)
Sensitivity aka efficiency is expressed in unit of dB SPL per mW. It indicates how efficient the coils in the headphone could transform per unit power received into loundness of sound.
HE400se is quoted to have 91dB, which is less efficient than say 110dB but by no means low efficiency. Sensitivity metrics is of secondary or tertiary order of importance IMO.
Compared to speakers, 91dB/V would be quite efficient, yes.
Also mind decibel is logarithmic, so 10 to 20dB is a 10x jump in power.
Since only few amp manufacturers bother to give compliance voltage (= peak output voltage), it is the second most important metric to estimate power requirements after impedance.
Doesn’t matter much for headphones TBF. Manufacturing capability improved a lot in the past three decades. I would assert even cheap ones are >= 90dB.
Also given say 1mW delivered to your headphones, comfortable listening dB will be way below 90dB.
Thanks, ill wait until they arrive to see how they go if i need an amp ill probably go for a fiio k3
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