Both are audio interfaces, $199 against $194. 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 Audient iD4 MkII reaches 100 dB on 561 of the 567 models here, the Steinberg UR24C on 558.
| Specification | Audient iD4 MkII | Steinberg UR24C |
|---|---|---|
| Power into 32Ω | 112 mW | 80 mW |
| Power into 150Ω | 75 mW | 27 mW |
| Power into 300Ω | 55 mW | 13 mW |
| Power into 600Ω | 50 mW | 6.7 mW |
| Output impedance | not published | not published |
| Output noise | not published | not published |
| Price | $199 | $194 |
| Headphones it reaches 100 dB on out of 567 | 561 | 558 |
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.
3 headphones reach 100 dB on the Audient iD4 MkII but not on the Steinberg UR24C — Moondrop PARA 2, Moondrop VENUS, Symphonium Triton.
558 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: Audient iD4 MkII and Steinberg UR24C. Or put either against your own headphones in the source comparison tool.