Audient EVO 4 vs IK Multimedia AXE I/O ONE

Short answer

Power: about the same. The Audient EVO 4 has 22 mW into 32 Ω, the IK Multimedia AXE I/O ONE 26 mW. The IK Multimedia AXE I/O ONE drives 7 headphones to 100 dB that the Audient EVO 4 cannot (Dan Clark Audio AEON 2 Closed, Dan Clark Audio AEON 2 Noire, Dan Clark Audio AEON 2 Open, 4 more).
Hiss with sensitive IEMs: cannot be compared — neither maker publishes a noise figure.
Output impedance: 561 headphones are left alone by the IK Multimedia AXE I/O ONE under the one-eighth rule but coloured by the Audient EVO 4 (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Nio, 558 more).
Price: the IK Multimedia AXE I/O ONE costs $1 more; what that buys on these numbers is set out further down, under What the price difference buys.

Both are audio interfaces, $129 against $130.

The IK Multimedia AXE I/O ONE reaches 100 dB on 550 of the 567 models here, the Audient EVO 4 on 543.

Every published figure, next to each other

Specification	Audient EVO 4	IK Multimedia AXE I/O ONE
Power into 32Ω	22 mW	26 mW
Power into 150Ω	14 mW	13 mW
Power into 300Ω	11 mW	6.7 mW
Power into 600Ω	10 mW	3.3 mW
Output impedance	50 Ω	<0.1 Ω
Output noise	not published	not published
Price	$129	$130
Headphones it reaches 100 dB on out of 567	543	550

Not published means the maker leaves it out, so that axis cannot be compared.

Where each power figure comes from

Load	Audient EVO 4	IK Multimedia AXE I/O ONE
32 Ω	Derived	Derived
150 Ω	Derived	Derived
300 Ω	Derived	Derived
600 Ω	Recomputed	Derived

Neither column is a maker’s power rating at these loads. Of the 280 sources here, 209 publish a figure at at least one load; these two do not, so every row above is derived — between or beyond the loads each maker did publish, holding output voltage as the maker’s own figures imply. The method understates rather than flatters, but it is still arithmetic rather than a rating.

What the labels mean.

The headphones that tell them apart

7 headphones reach 100 dB on the IK Multimedia AXE I/O ONE but not on the Audient EVO 4 — Dan Clark Audio AEON 2 Closed, Dan Clark Audio AEON 2 Noire, Dan Clark Audio AEON 2 Open, 4 more.

561 headphones are left alone by the IK Multimedia AXE I/O ONE under the one-eighth rule but coloured by the Audient EVO 4 (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Nio, 558 more).

543 of the 567 models here reach 100 dB on both.

Headroom and hiss on 8 models, both sources

Headroom is at a 100 dB SPL peak.

The widest gap on the list is the Audio-Technica ATH-R70X: Audient EVO 4 has +8 dB of headroom there against +4 dB. 4 dB is about 2.4 times the power, which matters for peaks rather than for how loud the music sits.

The hiss columns are empty for Audient EVO 4 and IK Multimedia AXE I/O ONE because neither maker publishes no output noise figure.

Headphone	Impedance	Needs	Audient EVO 4 headroom	IK Multimedia AXE I/O ONE headroom	Audient EVO 4 hiss	IK Multimedia AXE I/O ONE hiss
Shure SE846	9 Ω	0.04 mW	+22 dB damping	+23 dB	not published	not published
Campfire Audio Andromeda 2020	9 Ω	4.0 mW	+2 dB damping	+3 dB	not published	not published
Audeze LCD-2 Classic	70 Ω	0.79 mW	+15 dB damping	+16 dB	not published	not published
Beyerdynamic DT 1990 Pro (250Ω)	250 Ω	0.63 mW	+13 dB damping	+11 dB	not published	not published
HiFiMAN HE400se	25 Ω	7.9 mW	+4 dB damping	+4 dB	not published	not published
Audio-Technica ATH-R70X	470 Ω	1.6 mW	+8 dB	+4 dB	not published	not published
Sennheiser HD 600	300 Ω	6.6 mW	+2 dB damping	+0 dB	not published	not published
HiFiMAN Susvara	60 Ω	50 mW	-3 dB damping	-2 dB	not published	not published

The gap in dollars, against the gap in numbers

The IK Multimedia AXE I/O ONE costs $1 more than the Audient EVO 4. Out of the 567 models here, that difference buys 7 more models driven to 100 dB and 561 more models left alone under the one-eighth rule.

Nothing runs the other way: there is no axis here on which the cheaper of the two does better.

Only published figures count here; blank axes are counted separately.