I see a lot of variance on people’s amp recommendations for products. It seems to me like a clean 1W into 32Ω is enough to drive the majority of headphones to 120db, which is extraordinarily loud to the point of being unlistenable. Tons of middle-tier desktop amps can handle going over 5W per channel at the same impedance and some even go over 10W. Are these wattages actually useful for anything? What wattage would set you up for any headphone, regardless of budget?
One consideration with power is that headroom is convenient. Nobody probably listens at 120dB peak spl for most music but there’s media like podcasts with low average volume, and significant EQ also means significant negative preamp. 120dB would basically satisfy my wants, 110dB is workable and 100dB peak would make me put artificial gain sometimes. Wattage limits are mostly hit by low impedance, low sensitivity headphones, but high impedance ones are capped by voltage instead.
Something to remember is that to avoid clipping you want something that’ll handle the loudest peaks in a song, rather than the average volume. For music with high dynamic range, this could be as much as something like 25dB higher than the actual average volume. So if you want to listen to something like classical and occasionally like to be able to push the volume loud to like 90dB, that means you might realistically want an amp capable of driving your headphones to 115dB.
And that’s if you’re not touching EQ and only listening stock. If your EQ has a +12dB bass shelf or something and -12dB of preamp gain, then now for the same situation you want your amp to be able to reach 127dB. 127dB takes a little over 4x as much power as 120dB, so if 1W is enough for 120dB, you’re looking at a little over 4W there.
So it’s not completely unfeasible to need that much with that combination of power hungry cans + listening loud + high dynamic range music + EQ. Realistically though I think most people over-estimate how much of that headroom they’ll actually need. Plenty of people listen to music with no more than say 15dB of dynamic range, listen at more moderate volumes, don’t touch EQ, and then still buy a massively overkill amp thinking they need the extra headroom.
4 volts RMS would be enough for 99% of headphone market, and this voltage is industry standard. If output impedance is low, it will be able to drive low impedance headphones.
For stuff people mention,like HE-6 might need more, I don’t have much experience. You can calculate loudness of headphone based on dB/V spec. Every doubling of voltage increases loudness by 3 dB
Doubling voltage increases loudness by 6dB. Doubling of power (watts) increases it by 3dB, but 2x voltage = 4x power.
HE6 is 89.7 dB/V SPL so 4V would be 101.7dB.
It’s not just about voltage, though, it’s also about current/power. Voltage is only really relevant for high impedance headphones. Low impedance, most amps will run out of power before they run out of voltage.
4V @16Ω is 1W. I have several little dongles here that have no problem doing 4V @300Ω into a HD600 or HD800S (53mW) but they can’t do 1W.
Most headphones, you don’t need 1W though. HE6 is a bit of an exception.
My bad for 3dB thing. I think current is consequence of voltage and if output impedance of amplifier is low, current is unaffected. If output impedance is comparable with load impedance, voltage and current arrived at load is reduced.
Thank you for spec for HE6. On paper it should be plenty loud at 4 V
This audeze article does a better job explaining the terms and how they relate to each with regards to how much power is needed better than I ever could.
https://www.audeze.com/blogs/technology-and-innovation/sensitivity-impedance-and-amplifier-power
If you find an amp that will power the tungsten headphones, there is no headphones that amp would not be able to power. The tungsten headphones are low sensitivity, and high impedance. They’re easily the most difficult headphones to power that I have ever seen.
This audeze article does a better job explaining the terms and how they relate to each with regards to how much power is needed better than I ever could.
It kinda does but IMO only to a point. And that point is where they claim that your amplifier should be able to handle transients that are 50 dB louder than the average SPL.
It would mean that if you listen to music at an average SPL of 80 dB, your amplifier should be able to output enough power for peaks up to 130 dB.
Let me give you some examples of how much power would that be for some headphones (based on measurements from SoundStage Network or RAA):
~60 mW for very sensitive IEMs like KZ CRN.
~1.3 W(!) for a low sensitivity planar IEM like 7Hz Timeless.
~1 W for popular sensitive headphones like ATH M50x.
~126 W (a hundred and twenty six Watts) for one of the least sensitive headphones on the market like Hifiman HE6se.
What? A 126 W into the headphones?
If you want to get them to 130 dB - yes. Exponential growth goes wild.
Since power goes up exponentially with perceived volume, it really depends on how loud you listen. 120dB would be *way* overkill for me personally, 100dB peak SPL would be more than enough. That’s a huge difference in power.
I would say that if your amp can drive the Susvara well, it can drive just about everything, so that might be a solid benchmark.
Oh yes, I’m aware of the exponential nature of power growth. I gave 120db as an example of the extreme upper limit of loudness. Even the Susvara needs only 1.6W to reach 115db, which is still extraordinarily loud and gives you adequate headroom for listening at reasonable levels like <90dB. So why do amps that provide 5W or more need to exist?
One thing I’ve learned going to headphone meets is that some people like to listen at volumes I would personally consider punishing. While I don’t think that’s a great idea if you value your hearing, I’m not their mom.
Then of course, there’s the marketing question. Moar watts, moar better - never mind that going from 2W to 5W gives you a pretty meager increase in perceived volume (again that exponential thing - you need a difference of like 5x-10x in power to actually get a meaty increase in headroom) and that the average person is probably never coming anywhere close to the headroom limit anyway.