IK Multimedia AXE I/O: power output and what it will drive

The IK Multimedia AXE I/O is an audio interface at $400. It delivers 115 mW into 32Ω and 30 mW into 300Ω, which ranks it 204 of 280 for raw power among the sources in this database.

Measured at 100 dB SPL it has comfortable headroom on 527 of the 567 dynamic and planar headphones catalogued here, enough but not generous on 30, only marginal on 4 and not enough power for 6. Power is published at 50Ω; the rest of the table is derived from those figures. Output noise is not published, so the hiss estimate cannot be run.

What it actually puts out

TypeAudio interface
Price$400
Power into 32 Ω115 mW
Power into 150 Ω60 mW
Power into 300 Ω30 mW
Power into 600 Ω15 mW
Output impedance<0.1 Ω
Output noisenot published
Comfortable headroom on 527 of 567 headphones (93%) · short of power on 6

Where these numbers come from

The manufacturer publishes 180 mW into 50Ω. The rest of the table is worked out from those.

Derived rows hold output voltage steady, as an amplifier does (method).

Source: ikmultimedia.com.

LoadPowerStatusHow it was arrived at
32 Ω115 mWDerivedbeyond the published loads, holding output voltage constant — which understates rather than flatters
50 Ω180 mWPublishedthe manufacturer publishes this figure at this exact load
150 Ω60 mWDerivedbeyond the published loads, holding output voltage constant — which understates rather than flatters
300 Ω30 mWDerivedbeyond the published loads, holding output voltage constant — which understates rather than flatters
600 Ω15 mWDerivedbeyond the published loads, holding output voltage constant — which understates rather than flatters

Against 40 well-known headphones

Easiest to hardest to drive, with headroom at a 100 dB SPL peak.

HeadphoneImpedanceSensitivityNeedsHeadroomVerdict
Shure SE8469 Ω114.0 dB/mW0.04 mW+29 dBComfortable
64 Audio U12t12.6 Ω108.0 dB/mW0.16 mW+25 dBComfortable
Shure SE21517 Ω107.0 dB/mW0.20 mW+25 dBComfortable
Moondrop Aria32 Ω107.1 dB/mW0.19 mW+28 dBComfortable
Audeze LCD-X 202120 Ω103.0 dB/mW0.50 mW+22 dBComfortable
Truthear Hexa20.5 Ω103.1 dB/mW0.49 mW+22 dBComfortable
Sennheiser IE 20018 Ω101.6 dB/mW0.69 mW+20 dBComfortable
Sony MDR-750663 Ω106.0 dB/mW0.25 mW+28 dBComfortable
Meze 99 Classics32 Ω103.0 dB/mW0.50 mW+24 dBComfortable
Focal Clear MG55 Ω104.0 dB/mW0.40 mW+26 dBComfortable
Philips SHP950032 Ω101.0 dB0.79 mW+22 dBComfortable
Focal Utopia80 Ω104.0 dB/mW0.40 mW+25 dBComfortable
Meze Empyrean32 Ω100.0 dB1.0 mW+21 dBComfortable
Campfire Audio Andromeda 20209 Ω94.0 dB4.0 mW+9 dBEnough
Etymotic ER2SE15 Ω96.0 dB/mW2.5 mW+13 dBComfortable
AKG K37132 Ω99.1 dB/mW1.2 mW+20 dBComfortable
Audio-Technica ATH-M50X38 Ω99.0 dB/mW1.3 mW+20 dBComfortable
Beyerdynamic DT 900 Pro X48 Ω100.0 dB/mW1.0 mW+22 dBComfortable
Audeze LCD-2 Classic70 Ω101.0 dB/mW0.79 mW+22 dBComfortable
Grado SR80x38 Ω98.0 dB/mW1.6 mW+19 dBComfortable
Sennheiser HD 560S120 Ω100.8 dB/mW0.83 mW+20 dBComfortable
HiFiMAN Edition XS18 Ω92.0 dB6.3 mW+10 dBComfortable
HiFiMAN Arya Stealth32 Ω94.0 dB4.0 mW+15 dBComfortable
Dan Clark Audio AEON 2 Closed13 Ω90.0 dB/mW10 mW+7 dBEnough
Audeze LCD-514 Ω90.0 dB/mW10 mW+7 dBEnough
Beyerdynamic DT 1990 Pro (250Ω)250 Ω102.0 dB/mW0.63 mW+18 dBComfortable
HiFiMAN HE400se25 Ω91.0 dB7.9 mW+11 dBComfortable
HiFiMAN Sundara32 Ω92.0 dB6.3 mW+13 dBComfortable
Dan Clark Audio Stealth23 Ω90.0 dB/mW10 mW+9 dBEnough
Fostex T50RP MK350 Ω92.0 dB/mW6.3 mW+15 dBComfortable
AKG K70262 Ω92.9 dB/mW5.1 mW+15 dBComfortable
ZMF Verite Closed300 Ω99.0 dB/mW1.3 mW+14 dBComfortable
Sennheiser HD 650300 Ω97.8 dB/mW1.7 mW+13 dBComfortable
Sennheiser HD 800S300 Ω96.8 dB/mW2.1 mW+12 dBComfortable
Beyerdynamic DT 770 Pro (250Ω)250 Ω96.0 dB2.5 mW+12 dBComfortable
Audio-Technica ATH-R70X470 Ω98.0 dB/mW1.6 mW+11 dBComfortable
ZMF Atrium300 Ω96.0 dB/mW2.5 mW+11 dBComfortable
Abyss AB-1266 Phi TC50 Ω88.0 dB/mW16 mW+11 dBComfortable
Sennheiser HD 600300 Ω91.8 dB/mW6.6 mW+7 dBEnough
HiFiMAN Susvara60 Ω83.0 dB50 mW+5 dBEnough

Will it hiss?

The manufacturer does not publish an output noise figure for this source, so there is no hiss estimate here. If you have a measured figure, the hiss calculator takes it.

Output impedance and the one-eighth rule

At 0Ω output impedance this source satisfies the one-eighth rule with every headphone in the database, down to the 3Ω in-ears. Nothing here will have its frequency response shaped by the source.

Check any pair.

The cheapest thing here that does the same job

SourceTypePriceInto 300 ΩOutput impedanceOutput noise
FiiO KA5USB dongle$9914 mW0.3 Ω1.6 µV
Schiit Magni Heresydesktop amplifier$99410 mW0.25 Ω1.5 µV unverified
Schiit Magni Unitydesktop amplifier$119415 mW0.1 Ω1.59 µV

Of the 280 sources here, 17 do everything the IK Multimedia AXE I/O does as a headphone output: reach 100 dB on every headphone it reaches and stay inside the one-eighth rule wherever it does. The cheapest of them is the FiiO KA5 at $99, against this one’s $400 — $301 less, and a USB dongle rather than an audio interface.

The cheaper one also publishes a noise figure, which the IK Multimedia AXE I/O does not — so on the paperwork it is ahead, not merely level.

This counts the headphone output only; inputs, converters, the volume control and the build are outside it.

Other audio interfaces at a similar price

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