AKG K371: how much amplifier do you need?

The AKG K371 is 32Ω with a sensitivity of 99.0 dB/mW, which is 113.9 dB/V. To reach 100 dB SPL — genuinely loud, louder than most people listen — it needs 1.3 mW, or 0.20 V across the drivers.

That puts it in the easy category. A phone, a laptop headphone jack or the cheapest USB dongle will drive it to painful levels. Of the 53 sources in the database, 53 have comfortable headroom. The cheapest portable source that does the job is the Apple USB-C dongle (US) at $9.

The two numbers that decide everything

Impedance32 Ω
Sensitivity99.0 dB/mW
Sensitivity (voltage)113.9 dB/V
TypeOver-ear
BrandAKG
Easy to drive — anything will do it

Sensitivity here is in dB per milliwatt. Manufacturers often quote dB per volt instead and leave the unit off, which is the single most common reason online calculators give answers that are 10–15 dB wrong. The converter explains the difference.

Power, voltage and current by listening level

LevelWhat it isPowerVoltageCurrent
85 dB SPLquiet background listening0.04 mW36 mV1.1 mA
95 dB SPLnormal listening0.40 mW0.11 V3.5 mA
100 dB SPLloud listening1.3 mW0.20 V6.3 mA
105 dB SPLvery loud4.0 mW0.36 V11.2 mA
110 dB SPLpeaks on dynamic music13 mW0.63 V19.8 mA

Most people listen between 75 and 85 dB. The 100 dB row is the one worth planning around: it gives you headroom for dynamic peaks without designing your system for a volume that would damage your hearing in under fifteen minutes. The safe listening calculator puts numbers on that.

What drives them, from a $9 dongle upwards

Every source in the database, judged at 100 dB SPL into 32Ω. “Headroom” is how much power is left over above what the headphone needs — 10 dB means ten times the required power, which is what you want for dynamic peaks.

SourceTypePricePower into 32ΩHeadroomVerdict
Schiit Ragnarok 2desktop amplifier$150024.0 W+43 dBComfortable
Schiit Mjolnir 3desktop amplifier$8008.0 W+38 dBComfortable audible hiss
Burson Soloist 3X GTdesktop amplifier$15008.0 W+38 dBComfortable
Chord Hugo TT 2desktop amplifier$50008.0 W+38 dBComfortable
Schiit Asgard 3desktop amplifier$2507.0 W+37 dBComfortable
Ferrum OORdesktop amplifier$18007.0 W+37 dBComfortable
Topping A90 Discretedesktop amplifier$4006.0 W+37 dBComfortable
Wells Audio Milodesktop amplifier$25006.0 W+37 dBComfortable
Topping A90desktop amplifier$5005.5 W+36 dBComfortable
Headamp GS-X Minidesktop amplifier$14005.0 W+36 dBComfortable
JDS Labs Element III MK2desktop DAC/amp$3504.6 W+36 dBComfortable
SMSL HO200desktop amplifier$3004.0 W+35 dBComfortable
iFi iCAN Prodesktop amplifier$6004.0 W+35 dBComfortable audible hiss
Topping L30 IIdesktop amplifier$1303.5 W+34 dBComfortable
Cayin HA-6Adesktop amplifier$18003.0 W+34 dBComfortable audible hiss
FiiO M17portable player$18003.0 W+34 dBComfortable faint hiss
Schiit Magni+desktop amplifier$1092.0 W+32 dBComfortable
Fiio K7desktop DAC/amp$1802.0 W+32 dBComfortable
Fiio K9 Prodesktop DAC/amp$3802.0 W+32 dBComfortable
Geshelli Archel Prodesktop amplifier$2001.8 W+32 dBComfortable
Schiit Magni Heresydesktop amplifier$1001.6 W+31 dBComfortable
SMSL SH-9desktop amplifier$1501.5 W+31 dBComfortable
JDS Labs Atom+ (2nd gen)desktop amplifier$1001.0 W+29 dBComfortable
iFi Zen CANdesktop amplifier$2001.0 W+29 dBComfortable
HiBy R6 Pro IIportable player$750750 mW+28 dBComfortable faint hiss
FiiO M11Sportable player$500670 mW+27 dBComfortable faint hiss
FiiO KA17USB dongle$150650 mW+27 dBComfortable faint hiss
FiiO BTR17Bluetooth receiver$200650 mW+27 dBComfortable faint hiss
Astell&Kern SP3000portable player$3700600 mW+27 dBComfortable faint hiss
FiiO KA13USB dongle$80550 mW+26 dBComfortable faint hiss
Qudelix T71Bluetooth receiver$200400 mW+25 dBComfortable faint hiss
Astell&Kern SR35portable player$800400 mW+25 dBComfortable faint hiss
FiiO BTR15Bluetooth receiver$110340 mW+24 dBComfortable faint hiss
FiiO BTR7Bluetooth receiver$200320 mW+24 dBComfortable faint hiss
Questyle M15USB dongle$250300 mW+24 dBComfortable faint hiss
Hidizs S9 ProUSB dongle$75270 mW+23 dBComfortable faint hiss
Sony NW-WM1AM2portable player$1400250 mW+23 dBComfortable faint hiss
Qudelix 5KBluetooth receiver$110240 mW+23 dBComfortable faint hiss
Moondrop Dawn ProUSB dongle$60230 mW+23 dBComfortable faint hiss
iBasso DC04 ProUSB dongle$90230 mW+23 dBComfortable faint hiss
Shanling UP5Bluetooth receiver$130230 mW+23 dBComfortable faint hiss
Truthear SHIOUSB dongle$70213 mW+22 dBComfortable
Schiit Vali 2+desktop amplifier$200200 mW+22 dBComfortable audible hiss, damping
FiiO KA11USB dongle$30200 mW+22 dBComfortable faint hiss
ddHiFi TC44 ProUSB dongle$110190 mW+22 dBComfortable faint hiss
Shanling UA5Bluetooth receiver$220180 mW+22 dBComfortable faint hiss
Tempotec Sonata BHD ProUSB dongle$40130 mW+20 dBComfortable faint hiss
iBasso DC03 ProUSB dongle$60120 mW+20 dBComfortable faint hiss
Generic CX31993 donglesUSB dongle$1260 mW+17 dBComfortable audible hiss
EarStudio ES100 MK2Bluetooth receiver$9060 mW+17 dBComfortable faint hiss
Sony NW-A306portable player$35050 mW+16 dBComfortable faint hiss
Apple USB-C dongle (US)USB dongle$930 mW+14 dBComfortable faint hiss
Apple USB-C dongle (EU)USB dongle$915 mW+11 dBComfortable faint hiss

The three ways a source goes wrong

Hiss. At 113.9 dB/V these are sensitive enough to reveal a source's own noise floor. The noisiest source in the database, the Schiit Vali 2+, would put its hiss at roughly 22 dB SPL in these headphones — clearly audible in quiet passages. The hiss calculator lets you check your own amplifier's noise figure.

Output impedance. At 32Ω these want a source output impedance below 4.00Ω to satisfy the one-eighth rule. 1 of the 53 sources here miss it, the worst being the Schiit Vali 2+ at 6Ω. Above that threshold the source starts shaping the frequency response. Check yours here.

Similar headphones

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