Audient iD4 MkII: power output and what it will drive

The Audient iD4 MkII is a audio interface at $199. It delivers 112 mW into 32Ω and 55 mW into 300Ω, which ranks it 127 of 156 for raw power among the sources in this database.

Measured at 100 dB SPL it has comfortable headroom on 371 of the 396 dynamic and planar headphones catalogued here, enough but not generous on 23 and not enough power for 2.

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 half of what 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 figure is the peak voltage squared over the load, which is not what power means. On the iD4 MkII, 2.59 V peak into 30Ω gives 223 mW, exactly the number Audient prints, while the 1.827 Vrms printed beside it gives 111 mW. The same relation holds on all nine published points across the iD4 MkII, iD24 and EVO 4, so this is a formula error rather than a different rating condition. The voltages Audient prints are correct, and they are what the matching maths here actually uses.

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 HE-6se 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.

Or put any two side by side in the source comparison tool, or run your own headphones through the amplifier matcher.