Short answer
Both are audio interfaces, $130 against $200.
The IK Multimedia AXE I/O ONE reaches 100 dB on 550 of the 567 models here, the Zoom AMS-44 on 549.
| Specification | IK Multimedia AXE I/O ONE | Zoom AMS-44 |
|---|---|---|
| Power into 32Ω | 26 mW | 30 mW |
| Power into 150Ω | 13 mW | 9.7 mW |
| Power into 300Ω | 6.7 mW | 5.2 mW |
| Power into 600Ω | 3.3 mW | 2.7 mW |
| Output impedance | <0.1 Ω | 10 Ω |
| Output noise | not published | not published |
| Price | $130 | $200 |
| Headphones it reaches 100 dB on out of 567 | 550 | 549 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Load | IK Multimedia AXE I/O ONE | Zoom AMS-44 |
|---|---|---|
| 32 Ω | Derived | Published |
| 150 Ω | Derived | Derived |
| 300 Ω | Derived | Derived |
| 600 Ω | Derived | Derived |
Only one of these two columns starts from a power rating. Zoom AMS-44 publishes one at 32 Ω; IK Multimedia AXE I/O ONE publishes none at any of these four loads, so its column is worked out from power it published at other loads. Both are arithmetic on a maker’s own figures rather than guesses, and the method used for the IK Multimedia AXE I/O ONE understates rather than flatters — but at 32 Ω is the only load here at which its maker can be held to a figure.
2 headphones reach 100 dB on the IK Multimedia AXE I/O ONE but not on the Zoom AMS-44 — HiFiMAN Susvara Unveiled, Sennheiser HD 600.
1 headphone reaches 100 dB on the Zoom AMS-44 but not on the IK Multimedia AXE I/O ONE — Symphonium Meteor.
510 headphones are left alone by the IK Multimedia AXE I/O ONE under the one-eighth rule but coloured by the Zoom AMS-44 (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Nio, 507 more).
548 of the 567 models here reach 100 dB on both.
Headroom is at a 100 dB SPL peak.
The widest gap on the list is the HiFiMAN Susvara: IK Multimedia AXE I/O ONE has -2 dB of headroom there against -4 dB. 3 dB is about 1.9 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for IK Multimedia AXE I/O ONE and Zoom AMS-44 because neither maker publishes no output noise figure.
| Headphone | Impedance | Needs | IK Multimedia AXE I/O ONE headroom | Zoom AMS-44 headroom | IK Multimedia AXE I/O ONE hiss | Zoom AMS-44 hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +23 dB | +23 dB damping | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +3 dB | +3 dB damping | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +16 dB | +13 dB damping | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +11 dB | +10 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +4 dB | +5 dB damping | not published | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +4 dB | +3 dB | not published | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +0 dB | -1 dB | not published | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | -2 dB | -4 dB damping | not published | not published |
The Zoom AMS-44 costs $70 more than the IK Multimedia AXE I/O ONE. Out of the 567 models here, that difference buys 1 more model driven to 100 dB.
It does not run one way only: the cheaper IK Multimedia AXE I/O ONE drives 2 models to 100 dB and leaves 510 alone under the one-eighth rule that the Zoom AMS-44 does not, which is the part worth checking against your own headphones before paying the difference.
Only published figures count here; blank axes are counted separately.
Each in full: IK Multimedia AXE I/O ONE and Zoom AMS-44.