Free Calculator

Headphone Amplifier Power Calculator

How much amplifier your headphones actually need, and whether the source you already own can deliver it. Picks the right crest factor for your music, the right level for your listening, and tells you in dB how much headroom your source has left.

My rigs

Save headphone+source pairings to compare any time. Build up a personal library you can revisit when you buy new gear.

Required power - -

Drive difficulty

- -

Your source - Pick a source on the right to check voltage swing vs your headphone.

Your headphone

load

Headphone

Sensitivity

dB/V is what dongle outputs see directly. dB/mW is the older convention.

Impedance

Listening goal

target

Listening level

Custom

dB SPL

What you listen to

Custom crest

Your source

drive

Source / amp

Pick a DAC, dongle, or desktop amp. The compatibility check above updates against its max RMS output voltage.

Max output (RMS)

Manufacturer-rated max RMS at the load impedance, ideally measured. Spec sheets sometimes list "max output voltage" or "max output level".

SPL at each volume position

live

How loud your headphone gets at each position of the source's volume control, plotted against output voltage. The orange line is the actual SPL curve; the green dashed line is the WHO safe-listening anchor (85 dB); the accent line is your target including crest factor. Where they cross is the volume position you need to set.

Show the math

The headphone power math, demystified

From sensitivity to required power

For dBSPL/mW sensitivity, required power is P = 10^((target − sensitivity + crest) ÷ 10) mW. The corresponding RMS voltage drops out of Ohm's law: V = √(P × Z) with P in watts and Z in ohms.

For dBSPL/V sensitivity, required voltage is V = 10^((target − sensitivity + crest) ÷ 20), and power follows from P = V² ÷ Z.

Converting the two: dBSPL/V = dBSPL/mW + 10 × log10(Z ÷ 1000). At 300 Ω, dB/V is 5.2 dB lower than dB/mW.

Crest factor: why music needs more headroom than a sine wave

Music isn't a steady tone. Classical recordings can have 18 dB between the average level and the loudest transients; pop and rock typically 8-12 dB; modern EDM is squashed to 4-6 dB. To hear an average loudness of 85 dB without the loudest peak clipping your amp, you need the amp's clean output to reach the average level plus the crest factor.

Pick a genre above and the calculator picks the right crest factor; the requirement jumps accordingly. The math is the same as +1 dB SPL on the sensitivity figure - but the genre presets make it obvious why classical reference monitoring asks for so much more amp than EDM at the same average level.

Reference headphones, by what they need

Plug any of these into the calculator above and see exactly which amplifier tier the result lands in. Sensitivity figures are manufacturer specs at the listed reference; impedance is the rated nominal value.

Headphone	Sensitivity	Impedance	What drives it
Apple EarPods (3.5 mm)	109 dB/V	23 Ω	Phone or laptop jack - that's the design target.
Sennheiser HD 600	97 dB/V	300 Ω	Mid-tier desktop amp; phones run out of voltage.
Sennheiser HD 800 S	102 dB/V	300 Ω	Mid-tier desktop amp with clean voltage swing.
Beyerdynamic DT 880 (600 Ω)	96 dB/V	600 Ω	Voltage-rich amp - V swing is everything.
HIFIMAN Arya Organic	94 dB/mW	16 Ω	Capable dongle through entry desktop amp.
Audeze LCD-X	103 dB/mW	20 Ω	Easy on paper, but rewards higher current.
HIFIMAN HE6se V2	83.5 dB/mW	50 Ω	Speaker amp via TRS or proper headphone power amp.
HIFIMAN Susvara	83 dB/mW	60 Ω	Speaker-tap power amp; 1-2 W minimum at 60 Ω.

FAQ

Headphone power FAQ.

Required mW for hard-to-drive cans, what target SPL means in practice, and why dBSPL/mW is the better cross-impedance metric.

How do I calculate the amplifier power my headphones need?
Enter the headphone sensitivity (dB SPL/mW or dB SPL/V), impedance (ohms), and target SPL at your ears (typically 100-110 dB peak for music with 20 dB headroom). The calculator returns required power in milliwatts and the corresponding output voltage. Match an amp that exceeds the requirement at the headphone impedance.
What is a safe target SPL for headphones?
For long listening sessions, 70-80 dB SPL average is safe. Music has dynamic range, so the calculator factors in 15-20 dB of peak headroom on top of the average. WHO guidelines recommend keeping average levels below 80 dB to protect hearing - the safe-listening tool covers daily exposure time.
Why do high-impedance headphones need more amplifier power?
Power scales with voltage squared divided by impedance. Doubling impedance halves current at the same voltage, so a 600-ohm headphone needs roughly four times the voltage of a 150-ohm pair for the same SPL, assuming similar sensitivity per volt. Sensitivity per milliwatt is the better comparison metric across impedances.
How much amp headroom do I need over the calculated requirement?
A factor of 2-3x in power (3-5 dB) is the working minimum. Some amps soft-clip well; others go straight into hard distortion. If your headphone is a hard-to-drive planar like the HIFIMAN Susvara, target 4-6 W at 60 ohm and prefer a desktop amp over a dongle.
What headphone sensitivity spec should I trust on a spec sheet?
Sensitivity in dB SPL/mW is most useful for comparing across impedances. dB SPL/V is what dongle dacs and phone outputs see. Manufacturer numbers can be optimistic; if you have measurement data from third parties (Crinacle, Headphones.com), use those for the calculation instead.
Can I drive HIFIMAN Susvara or HE6 from a phone or dongle DAC?
No. The Susvara at 83 dB/mW and 60 Ω needs roughly 4-6 W into 60 Ω to hit 110 dB peaks, well beyond any dongle DAC or portable amp. The HE6se V2 sits in the same territory. Both want a real desktop amplifier - in practice, a 30 W per channel integrated or a dedicated headphone power amp like the Cayin Soul170HA, Riviera AIC-10, or even speaker taps on a tube amp.
Does balanced output give my headphones more power?
Yes - balanced topologies double the voltage swing, which quadruples available power into the same impedance (P scales with V²). Whether you need that depends on the headphone: hard-to-drive planars benefit, sensitive IEMs do not. The calculator returns the required figure regardless of whether the amp gets there single-ended or balanced.
Why does the same headphone need different power on different amps?
Because the amplifier output impedance interacts with the headphone impedance. The eight-to-one rule says amp output impedance should be at least one-eighth of the headphone impedance to keep the frequency response flat. A tube amp at 30 Ω driving a 32 Ω headphone shifts the bass; the same headphone on a 0.5 Ω solid-state output behaves as designed. The calculator gives you the floor; matching is the next step.