Short answer
Both are audio interfaces, both at $199.
The Focusrite Scarlett 2i2 4th gen reaches 100 dB on 552 of the 567 models here, the Steinberg UR22C on 512.
| Specification | Focusrite Scarlett 2i2 4th gen | Steinberg UR22C |
|---|---|---|
| Power into 32Ω | 31 mW | 12 mW |
| Power into 150Ω | 19 mW | 4.0 mW |
| Power into 300Ω | 22 mW | 2.0 mW |
| Power into 600Ω | 11 mW | 1.0 mW |
| Output impedance | 50 Ω | not published |
| Output noise | not published | not published |
| Price | $199 | $199 |
| Headphones it reaches 100 dB on out of 567 | 552 | 512 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Load | Focusrite Scarlett 2i2 4th gen | Steinberg UR22C |
|---|---|---|
| 32 Ω | Derived | Derived |
| 150 Ω | Derived | Derived |
| 300 Ω | Published | Derived |
| 600 Ω | Derived | Derived |
Only one of these two columns starts from a power rating. Focusrite Scarlett 2i2 4th gen publishes one at 300 Ω; Steinberg UR22C 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 Steinberg UR22C understates rather than flatters — but at 300 Ω is the only load here at which its maker can be held to a figure.
40 headphones reach 100 dB on the Focusrite Scarlett 2i2 4th gen but not on the Steinberg UR22C — AKG K612 Pro, Abyss AB-1266 Phi CC, Abyss AB-1266 Phi TC, 37 more.
512 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 Sennheiser HD 600: Focusrite Scarlett 2i2 4th gen has +5 dB of headroom there against -5 dB. 10 dB is about 11 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for Focusrite Scarlett 2i2 4th gen and Steinberg UR22C because neither maker publishes no output noise figure.
| Headphone | Impedance | Needs | Focusrite Scarlett 2i2 4th gen headroom | Steinberg UR22C headroom | Focusrite Scarlett 2i2 4th gen hiss | Steinberg UR22C hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +23 dB damping | +19 dB | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +3 dB damping | -1 dB | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +14 dB damping | +10 dB | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +15 dB damping | +6 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +5 dB damping | +1 dB | not published | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +9 dB | -1 dB | not published | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +5 dB damping | -5 dB | not published | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | -3 dB damping | -7 dB | not published | not published |
These two cost the same, $199, so price settles nothing. Out of the 567 models here, the Focusrite Scarlett 2i2 4th gen drives 40 models to 100 dB — and on the other side there is no such advantage at all.
Only published figures count here; blank axes are counted separately.
Each in full: Focusrite Scarlett 2i2 4th gen and Steinberg UR22C.