Audient iD4 MkII: power output and what it will drive

The Audient iD4 MkII is an audio interface at $199. It delivers 112 mW into 32Ω and 55 mW into 300Ω, which ranks it 206 of 280 for raw power among the sources in this database.

Measured at 100 dB SPL it has comfortable headroom on 528 of the 567 dynamic and planar headphones catalogued here, enough but not generous on 29, only marginal on 4 and not enough power for 6. Power is published at 30Ω, 62Ω, 600Ω; the rest of the table is derived from those figures. Output impedance is not published. Output noise is not published, so the hiss estimate cannot be run.

This entry does not repeat the manufacturer's printed power figures. It uses 111 mW into 30Ω, 140 mW into 62Ω, 50 mW into 600Ω.

The power figures above are not the ones Audient prints, and that is deliberate. Audient publishes a peak voltage, an RMS voltage and a power figure on the same line — and the power is twice what the RMS voltage gives. On the iD4 MkII, 1.827 Vrms into 30Ω is 111 mW; Audient prints 223 mW. The same factor runs through all nine published points across the iD4 MkII, iD24 and EVO 4 — six of them within 1% of 2.00 and the other three 3–6% below it, the sort of spread two- and three-digit printed figures produce — so it is systematic rather than a slip on one line. Two things would produce it: squaring the peak voltage instead of the RMS one, or quoting both channels added together. The arithmetic cannot tell those apart — V_pk²/R and 2·V_rms²/R are the same number — and Audient does not say which it is. So this database does not guess at the cause. It applies one rule that follows straight from their own document: the power here is V_rms²/R computed from the RMS voltage Audient prints beside each load. That comes out at half the printed power, give or take the rounding of their figures. The voltages themselves are untouched, and they are what the matching maths on this page relies on.

Derivation holds output voltage steady between and beyond the published loads rather than output power, because that is what an amplifier actually does. The full method is written up here.

Source: support.audient.com, audient.com.

Ordered from easiest to hardest to drive. Headroom is measured at 100 dB SPL, which is louder than almost anyone listens — a small negative number means the source still plays loud, just without reserve for peaks.

These figures come from each manufacturer's own sensitivity rating. A handful of planars — the HiFiMAN Susvara and the Abyss AB-1266 in particular — are widely reported to need far more than their published sensitivity implies, so treat a bare pass on those as optimistic rather than settled.

The manufacturer does not publish an output noise figure for this source, so the hiss estimate that runs on every other page here cannot be run on this one. Rather than substitute a plausible number, this page leaves the question open.

If you know the noise figure from a measurement you trust, the hiss calculator takes it directly and tells you where that noise lands in your own in-ears.

The manufacturer does not publish an output impedance for this source. That is the one number that decides whether it leaves your headphones alone or acts as a tone control, so its absence matters more than it looks: without it, nothing here can tell you how this source will behave with a multi-driver in-ear.

If you find a measured figure you trust, the checker will work out the consequence for any headphone.

Of the 280 sources here, 46 do everything the Audient iD4 MkII does as a headphone output: reach 100 dB on every headphone it reaches. The cheapest of them is the FiiO KA11 at $29, against this one’s $199 — $170 less, and a USB dongle rather than an audio interface.

The cheaper one also publishes an output impedance and a noise figure, which the Audient iD4 MkII does not — so on the paperwork it is ahead, not merely level.

This counts a headphone output and nothing else. Inputs, converters, microphone preamps, balanced outputs, the volume control, the case and the warranty are all outside it, and any of them can be the reason to buy the dearer box. What the count does say is that the three numbers a maker can be held to do not separate them.

Worked out in advance against its closest rivals: vs Audient EVO 16 · vs Audient EVO 4 · vs Audient EVO 8 · vs Audient Horizon 8P · vs Audient iD44 MkII · vs Audient iD48 · vs Audient NERO · vs Audient ORIA · vs Focusrite Scarlett 2i2 4th gen · vs Steinberg UR22C · vs Steinberg UR24C · vs Tascam US-2x2HR · vs Universal Audio Volt 2 · vs Zoom AMS-44. Each of those pages lists the headphones that tell the two apart.

Or put any two side by side in the source comparison tool, or run your own headphones through the amplifier matcher. Or see every Audient source in the database, and how much of what this site says about them came from Audient’s own documents.