tamirci said:

  I am telling this because 400s has a power input of 4W*. Being a planar magnet one could see it coming
Magni 2 is powerful yeah. But not something to feed 400s fully. It can only supply about 1/3 of the power 400s can handle.
* I asked HIHIman directly and this was their answer.

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How much power a headphone can "handle" (i.e., how much it takes before it starts to get damaged), and how much power you want to give it for reasonable listening levels are two entirely different things. That said, I suppose it depends on how loud you like to listen.
 
4W of power into a 22 Ohm headphone will be roughly 9.38 Volts (from Ohm's law). Since the HE-400S have a sensitivity of 98dB/V, we get 98 + 20*log(9.3) = 117.4 dB SPL peak volume. The Magni 2's roughly 1.5W of power at 22 Ohms (not exact, but it gives 1.2W @ 32 Ohms and 1.8W @ 16 Ohms) would give you 113.2 dB SPL. You can easily damage your hearing listening to anything at average levels over 100 dB SPL with regularity, so unless you like to play things at crazy loud levels, any amp that can cleanly deliver even 1W into 22O (resulting in 111.4 dB SPL max) should be fine, and give you plenty of headroom for dynamic recordings.

mejoshua said:

  You are right. Sorry if I did not make it clear in my previous post. Although I must say that what it means to fully "drive" the headphones may still ultimately be subjective. More power in watts does not necessarily equate to better sound either.

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Out hobby is subjective mostly yeah. But in my technical knowledge; if you don't push the throttle (and drive at 60mph maximum) of an e.g. Porche Carrera you can't have a fast car. If you don't supply a hp which craves for Ws, then it's the same! You'll just have a plain standart "good sounding" headphone. As more fuel is needed for an engine to see its true potential, more W's are needed for a headphone to see it's potential, expecially if it has a top power level of 4W

alamei said:

  How much power a headphone can "handle" (i.e., how much it takes before it starts to get damaged), and how much power you want to give it for reasonable listening levels are two entirely different things. That said, I suppose it depends on how loud you like to listen.
 
4W of power into a 22 Ohm headphone will be roughly 9.38 Volts (from Ohm's law). Since the HE-400S have a sensitivity of 98dB/V, we get 98 + 20*log(9.3) = 117.4 dB SPL peak volume. The Magni 2's roughly 1.5W of power at 22 Ohms (not exact, but it gives 1.2W @ 32 Ohms and 1.8W @ 16 Ohms) would give you 113.2 dB SPL. You can easily damage your hearing listening to anything at average levels over 100 dB SPL with regularity, so unless you like to play things at crazy loud levels, any amp that can cleanly deliver even 1W into 22O (resulting in 111.4 dB SPL max) should be fine, and give you plenty of headroom for dynamic recordings.

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Respect..I am not capable of such calculations.
 
Then I'll withdraw my comments.
Magni 2 is more than capable for He400s.

Any comparisons with the Yamaha MT220 and ESS RLM-713 ?

alamei said:

  How much power a headphone can "handle" (i.e., how much it takes before it starts to get damaged), and how much power you want to give it for reasonable listening levels are two entirely different things. That said, I suppose it depends on how loud you like to listen.
 
4W of power into a 22 Ohm headphone will be roughly 9.38 Volts (from Ohm's law). Since the HE-400S have a sensitivity of 98dB/V, we get 98 + 20*log(9.3) = 117.4 dB SPL peak volume. The Magni 2's roughly 1.5W of power at 22 Ohms (not exact, but it gives 1.2W @ 32 Ohms and 1.8W @ 16 Ohms) would give you 113.2 dB SPL. You can easily damage your hearing listening to anything at average levels over 100 dB SPL with regularity, so unless you like to play things at crazy loud levels, any amp that can cleanly deliver even 1W into 22O (resulting in 111.4 dB SPL max) should be fine, and give you plenty of headroom for dynamic recordings.

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Great math there man. So if u were to calculate in such way and decide an amp for the bigger brother i.e. 560. which Schiit would be fit for it ? Sorry for the Off Topic.

I only discover this thread now. 58 pages already, waw.
I received the 400S yesterday but haven't gotten further than unboxing it
I do have the full Hifiman lineup here, so I'll be comparing these to the rest when I get the time

richbass said:

 
Great math there man. So if u were to calculate in such way and decide an amp for the bigger brother i.e. 560. which Schiit would be fit for it ? Sorry for the Off Topic.

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I've never owned or tried the HE-560, so I can't say whether you'll like a particular amplifier pairing in terms of sound, but in terms of power, any Schiit amp will be fine.
 
HiFiMan isn't clear about the measurements for the HE-560 (dB/mW or dB/V), but since they say the "efficiency" of the 560 is 90 dB, and they use that to mean dB/mW elsewhere, I'll assume they're using dB/mW. That means, with an amplifier that provides 1W @ 50O (the lowest-end Schiit, Magni 2), you'll get 90 + 10*log(1000) = 120dB SPL. Again, that's more than enough to destroy your eardrums, so you can basically assume that anything you're considering will have all the power you need and then some.
 
On that note, as someone mentioned earlier in the thread, the 98dB/V spec for the 400S seems a bit suspect, since that would technically make them harder to drive than the 560. If you go by the alternately reported spec of 93dB/mW instead, a 1W input would result in 123dB SPL, and a 4W input would provide an ear-shattering 129dB SPL.

ultrainferno said:

  I only discover this thread now. 58 pages already, waw.
I received the 400S yesterday but haven't gotten further than unboxing it
I do have the full Hifiman lineup here, so I'll be comparing these to the rest when I get the time

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Looking forward to you sharing your impressions & comparisons across the full line!!

I'm really happy with this 400S.
From Queen to Ennio Morricone, this headphone sound good with all type music

ultrainferno said:

  I only discover this thread now. 58 pages already, waw.
I received the 400S yesterday but haven't gotten further than unboxing it
I do have the full Hifiman lineup here, so I'll be comparing these to the rest when I get the time

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Does that include the 300? I currently have the 300 and 500, but have been listening more to my 300 lately because I prefer its darker sound to the 500's brighter sound. If you do have the 300, I'd like a comparison.

kewlmunky said:

 Does that include the 300? (snip) I prefer its darker sound. If you do have the 300, I'd like a comparison.

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Me too. I hear the sub bass reach, controlled mid bass aspects are there. My concern is HE400s being too bright. I'm into Shure SRH1540, Audeze LCD-2 sonics.

Can somebody talk about the build quality of 400S? I know they have plastic, but its something like the HD600/HD650 have to deliver better acustics at lower prices, but still are solid build?

music path said:

Can somebody talk about the build quality of 400S? I know they have plastic, but its something like the HD600/HD650 have to deliver better acustics at lower prices, but still are solid build?

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Build quality is very good imo. Very good sounding headphone at a great price for planar. Definitely need amplification though.

I have a pair of HE400S on the way. Will a CayinC5 power it? O_o

formula said:

I have a pair of HE400S on the way. Will a CayinC5 power it? O_o

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Yes. It helps even he500 to drive properly. I think there will be sufficient power to be driven. Welcome aboard!