Both are audio interfaces, $279 against $199. 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 MOTU M4 reaches 100 dB on 565 of the 567 models here, the Steinberg UR22C on 512.
| Specification | MOTU M4 | Steinberg UR22C |
|---|---|---|
| Power into 32Ω | 333 mW | 12 mW |
| Power into 150Ω | 71 mW | 4.0 mW |
| Power into 300Ω | 36 mW | 2.0 mW |
| Power into 600Ω | 18 mW | 1.0 mW |
| Output impedance | not published | not published |
| Output noise | not published | not published |
| Price | $279 | $199 |
| Headphones it reaches 100 dB on out of 567 | 565 | 512 |
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.
53 headphones reach 100 dB on the MOTU M4 but not on the Steinberg UR22C — AKG K612 Pro, Abyss AB-1266 Phi CC, Abyss AB-1266 Phi TC, 50 more.
512 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: MOTU M4 and Steinberg UR22C. Or put either against your own headphones in the source comparison tool.