Both are audio interfaces, $400 against $399. This page puts them side by side on the only three things a maker can be held to — power, output impedance and noise — and then asks the question that actually matters: which headphones do they treat differently?
The Zoom UAC-232 reaches 100 dB on 563 of the 567 models here, the IK Multimedia AXE I/O on 561.
| Specification | IK Multimedia AXE I/O | Zoom UAC-232 |
|---|---|---|
| Power into 32Ω | 115 mW | 148 mW |
| Power into 150Ω | 60 mW | 51 mW |
| Power into 300Ω | 30 mW | 28 mW |
| Power into 600Ω | 15 mW | 14 mW |
| Output impedance | <0.1 Ω | 12 Ω |
| Output noise | not published | not published |
| Price | $400 | $399 |
| Headphones it reaches 100 dB on out of 567 | 561 | 563 |
A figure marked not published is missing from the maker’s own material, which is not the same as being good or bad. Where one of these two publishes a number and the other does not, the comparison on that axis cannot be made at all — and saying so is more useful than guessing.
2 headphones reach 100 dB on the Zoom UAC-232 but not on the IK Multimedia AXE I/O — Moondrop COSMO, Symphonium Zenith.
520 headphones are left alone by the IK Multimedia AXE I/O under the one-eighth rule but coloured by the Zoom UAC-232 (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Nio, 517 more).
561 of the 567 models here reach 100 dB on both. That is a power count and nothing more; whether either source suits a given headphone also depends on the two lines above.
Each has a page of its own with every power figure traced to what the maker published and a full headphone list: IK Multimedia AXE I/O and Zoom UAC-232. Or put either against your own headphones in the source comparison tool.