Moondrop Armature Art 12: how much amplifier do you need?

The Moondrop Armature Art 12 is 5Ω with a sensitivity of 98.0 dB/mW, which is 121.0 dB/V. To reach 100 dB SPL — genuinely loud, louder than most people listen — it needs 1.6 mW, or 89 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, 223 have at least 10 dB of headroom and another 51 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

Impedance5 Ω
Sensitivity98.0 dB/mW
Sensitivity (voltage)121.0 dB/V
Power for 100 dB SPL1.6 mW
Voltage for 100 dB SPL89 mV
TypeIn-ear monitor
Easy to drive — anything will do it
All 280 sources at 100 dB SPL into 5Ω
Comfortable 223Enough 51Marginal 6Not enough 0
Cheapest portable source that does it
$9 · USB dongle · +5 dB headroom
Cheapest desktop amp with 10 dB to spare
$75 · desktop DAC/amp · +12 dB headroom

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

Where this sensitivity figure comes from

Moondrop publishes this as 121 dB / Vrms ((@1kHz)) — a figure per volt, not per milliwatt. At 5Ω the two differ by 23.0 dB, so the 98.0 dB/mW above is that published number converted, not a different measurement.

This is the conversion that online calculators skip. Quote the per-volt number as if it were per-milliwatt and this headphone looks 23 dB easier to drive than it is — which is roughly the difference between a dongle being enough and not being enough.

Moondrop prints the impedance as 5Ω±15% (@1kHz), not as a bare number. Everything on this page is calculated with the nominal 5Ω, and the rest of that line is quoted here rather than tidied away, because how a figure is qualified is part of the specification too.

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

What is printed there, and what it is worth

As it is labelledAs printedToleranceStandard
Frequency Response Range6Hz-34kHznot printednot printed
Effective Frequency Response Range20Hz-20kHz (IEC60318-4, -3dB)-3 dBIEC60318-4

Moondrop prints two frequency ranges for the Moondrop Armature Art 12. The wide one carries no conditions at all; the narrow one names a measurement standard and a tolerance. Only the second is a specification — the first is a headline.

This is one of only 58 models — out of the 490 whose maker prints a range at all — that also print the tolerance. That is what makes it a specification rather than a headline.

Only what the maker printed; maker by maker.

Power, voltage and current by listening level

LevelWhat it isPowerVoltageCurrent
85 dB SPLquiet background listening0.05 mW16 mV3.2 mA
95 dB SPLnormal listening0.50 mW50 mV10.0 mA
100 dB SPLloud listening1.6 mW89 mV17.8 mA
105 dB SPLvery loud5.0 mW0.16 V31.7 mA
110 dB SPLpeaks on dynamic music16 mW0.28 V56.3 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 5Ω 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 5ΩHeadroomVerdict
Tanchjim Stargate IIUSB dongle$4026 mW+12 dBComfortable
ddHiFi TC35ALUSB dongle$4633 mW+13 dBComfortable
ddHiFi TC35AirUSB dongle$4633 mW+13 dBComfortable
Fosi Audio N3Bluetooth receiver$5022 mW+11 dBComfortable
EPZ TP35 ProUSB dongle$7017 mW+10 dBComfortable
Aiyima A2 Prodesktop DAC/amp$7523 mW+12 dBComfortable
ddHiFi TC44 Pro E2USB dongle$9939 mW+14 dBComfortable
Onix Alpha XI1USB dongle$10928 mW+12 dBComfortable
Hidizs S9 Pro PlusUSB dongle$13922 mW+11 dBComfortable
Topping L30 IIdesktop amplifier$1491.1 W+28 dBComfortable
Shanling H2portable amplifier$169106 mW+18 dBComfortable
xDuoo MT-604desktop amplifier$169312 mW+23 dBComfortable
TempoTec Variations V3 Blazeportable player$179129 mW+19 dBComfortable
Surfans F28portable player$18020 mW+11 dBComfortable
Audient iD4 MkIIaudio interface$19919 mW+11 dBComfortable

The three ways a source goes wrong

Hiss. At 121.0 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 29 dB SPL in these headphones — clearly audible in quiet passages. Check your own source.

Output impedance. At 5Ω these want a source output impedance below 0.62Ω to satisfy the one-eighth rule; 95 of the 192 sources that publish one miss it. Check yours here.

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