Short answer
Both are audio interfaces, $129 against $100.
The Audient EVO 4 reaches 100 dB on 543 of the 567 models here, the Zoom AMS-22 on 538.
| Specification | Audient EVO 4 | Zoom AMS-22 |
|---|---|---|
| Power into 32Ω | 22 mW | 20 mW |
| Power into 150Ω | 14 mW | 6.5 mW |
| Power into 300Ω | 11 mW | 3.4 mW |
| Power into 600Ω | 10 mW | 1.8 mW |
| Output impedance | 50 Ω | 10 Ω |
| Output noise | not published | not published |
| Price | $129 | $100 |
| Headphones it reaches 100 dB on out of 567 | 543 | 538 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Load | Audient EVO 4 | Zoom AMS-22 |
|---|---|---|
| 32 Ω | Derived | Published |
| 150 Ω | Derived | Derived |
| 300 Ω | Derived | Derived |
| 600 Ω | Recomputed | Derived |
Only one of these two columns starts from a power rating. Zoom AMS-22 publishes one at 32 Ω; Audient EVO 4 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 Audient EVO 4 understates rather than flatters — but at 32 Ω is the only load here at which its maker can be held to a figure.
5 headphones reach 100 dB on the Audient EVO 4 but not on the Zoom AMS-22 — Abyss AB-1266 Phi TC, Audeze LCD-5, Beyerdynamic DT 880 Edition (600Ω), 2 more.
51 headphones are left alone by the Zoom AMS-22 under the one-eighth rule but coloured by the Audient EVO 4 (AKG K612 Pro, Audeze LCD-3, Audeze LCD-4, 48 more).
538 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 Audio-Technica ATH-R70X: Audient EVO 4 has +8 dB of headroom there against +2 dB. 7 dB is about 4.5 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 Zoom AMS-22 because neither maker publishes no output noise figure.
| Headphone | Impedance | Needs | Audient EVO 4 headroom | Zoom AMS-22 headroom | Audient EVO 4 hiss | Zoom AMS-22 hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +22 dB damping | +22 dB damping | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +2 dB damping | +2 dB damping | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +15 dB damping | +11 dB damping | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +13 dB damping | +8 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +4 dB damping | +3 dB damping | not published | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +8 dB | +2 dB | not published | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +2 dB damping | -3 dB | not published | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | -3 dB damping | -6 dB damping | not published | not published |
The Audient EVO 4 costs $29 more than the Zoom AMS-22. Out of the 567 models here, that difference buys 5 more models driven to 100 dB.
It does not run one way only: the cheaper Zoom AMS-22 leaves 51 models alone under the one-eighth rule that the Audient EVO 4 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: Audient EVO 4 and Zoom AMS-22.