Audient EVO 4: power output and what it will drive

The Audient EVO 4 is a audio interface at $129. It delivers 22 mW into 32Ω and 11 mW into 300Ω, which ranks it 152 of 156 for raw power among the sources in this database.

Measured at 100 dB SPL it has comfortable headroom on 240 of the 396 dynamic and planar headphones catalogued here, enough but not generous on 131, only marginal on 14 and not enough power for 11.

This entry does not repeat the manufacturer's printed power figures. It uses 22 mW into 30Ω, 26 mW into 60Ω, 10 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: 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.

At 50 Ω output impedance, the one-eighth rule says this source suits headphones of 400.0Ω and above. 390 of the 396 models here fall below that, mostly multi-driver in-ears, where the mismatch tilts the frequency response audibly rather than subtly.

The rule is a rule of thumb, not physics: a source impedance below one eighth of the headphone's keeps the interaction under about 1 dB. The checker works it out for any pair.

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