Kiwi Ears Orchestra II: how much amplifier do you need?

The Kiwi Ears Orchestra II is 15Ω with a sensitivity of 110.0 dB/mW, which is 128.2 dB/V. To reach 100 dB SPL — genuinely loud, louder than most people listen — it needs 0.10 mW, or 39 mV 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 280 sources in the database, 280 have at least 10 dB of headroom and another 0 have enough. The cheapest portable source that does the job is the Apple USB-C dongle (US) at $9.

The two numbers that decide everything

Impedance15 Ω
Sensitivity110.0 dB/mW
Sensitivity (voltage)128.2 dB/V
Power for 100 dB SPL0.10 mW
Voltage for 100 dB SPL39 mV
TypeIn-ear monitor
Easy to drive — anything will do it
All 280 sources at 100 dB SPL into 15Ω
Comfortable 280Enough 0Marginal 0Not enough 0
Cheapest portable source that does it
$9 · USB dongle · +21 dB headroom
Cheapest desktop amp with 10 dB to spare
$75 · desktop DAC/amp · +28 dB headroom

Sensitivity here is in dB per milliwatt. Why the unit matters.

Where this sensitivity figure comes from

Kiwi Ears publishes this directly as 110 dB SPL/mW, per milliwatt, so nothing was converted.

Source: kiwiears.com. How this data was built.

What is printed there, and what it is worth

As it is labelledAs printedToleranceStandard
Frequency Range20Hz-20KHznot printednot printed

Kiwi Ears prints 20Hz-20KHz for the Kiwi Ears Orchestra II, under the heading “Frequency Range”. Source: kiwiears.com.

No tolerance is printed with it, so “20Hz-20KHz” says nothing about how loud this headphone actually is at 20 Hz.

Only what the maker printed; maker by maker.

Power, voltage and current by listening level

LevelWhat it isPowerVoltageCurrent
85 dB SPLquiet background listening0.00 mW7 mV0.5 mA
95 dB SPLnormal listening0.03 mW22 mV1.5 mA
100 dB SPLloud listening0.10 mW39 mV2.6 mA
105 dB SPLvery loud0.32 mW69 mV4.6 mA
110 dB SPLpeaks on dynamic music1.0 mW0.12 V8.2 mA

Most people listen between 75 and 85 dB; the 100 dB row leaves room for peaks.

The cheapest sources that drive them with room to spare

The 15 cheapest of the 280 sources here that reach 100 dB SPL into 15Ω with at least 10 dB of headroom and no known hiss or output-impedance problem with these headphones. All 280 sources, judged for these headphones.

SourceTypePricePower into 15ΩHeadroomVerdict
FiiO SnowSky Tiny AUSB dongle$2242 mW+26 dBComfortable
FiiO SnowSky Tiny BUSB dongle$2264 mW+28 dBComfortable
Tanchjim Stargate IIUSB dongle$4077 mW+29 dBComfortable
ddHiFi TC35ALUSB dongle$4698 mW+30 dBComfortable
ddHiFi TC35AirUSB dongle$4698 mW+30 dBComfortable
Fosi Audio N3Bluetooth receiver$5065 mW+28 dBComfortable
Hidizs SD2USB dongle$5033 mW+25 dBComfortable
iFi GO linkUSB dongle$5933 mW+25 dBComfortable
Kiwi Ears Allegro ProUSB dongle$6032 mW+25 dBComfortable
ddHiFi TC35Pro (Mountain2)USB dongle$6630 mW+25 dBComfortable
DUNU DTC 480USB dongle$7030 mW+25 dBComfortable
EPZ TP35 ProUSB dongle$7053 mW+27 dBComfortable
Aiyima A2 Prodesktop DAC/amp$7570 mW+28 dBComfortable
ddHiFi TC35Pro (Eye2)USB dongle$7630 mW+25 dBComfortable
ddHiFi TC44 Pro E2USB dongle$99117 mW+31 dBComfortable

The three ways a source goes wrong

Hiss. At 128.2 dB/V these are sensitive enough to reveal a source's own noise floor. The noisiest source in the database, the Schiit Mjolnir 3, would put its hiss at roughly 36 dB SPL in these headphones — clearly audible in quiet passages. Check your own source.

Output impedance. At 15Ω these want a source output impedance below 1.88Ω to satisfy the one-eighth rule; 39 of the 192 sources that publish one miss it. Check yours here.

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