Short answer
Both are audio interfaces, $410 against $399.
The Zoom UAC-232 reaches 100 dB on 563 of the 567 models here, the Focusrite Scarlett 16i16 (4th Gen) on 553.
| Specification | Focusrite Scarlett 16i16 (4th Gen) | Zoom UAC-232 |
|---|---|---|
| Power into 32Ω | 55 mW | 148 mW |
| Power into 150Ω | 27 mW | 51 mW |
| Power into 300Ω | 27 mW | 28 mW |
| Power into 600Ω | 14 mW | 14 mW |
| Output impedance | 11 Ω | 12 Ω |
| Output noise | not published | not published |
| Price | $410 | $399 |
| Headphones it reaches 100 dB on out of 567 | 553 | 563 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Load | Focusrite Scarlett 16i16 (4th Gen) | Zoom UAC-232 |
|---|---|---|
| 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 16i16 (4th Gen) publishes one at 300 Ω; Zoom UAC-232 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 Zoom UAC-232 understates rather than flatters — but at 300 Ω is the only load here at which its maker can be held to a figure.
10 headphones reach 100 dB on the Zoom UAC-232 but not on the Focusrite Scarlett 16i16 (4th Gen) — HiFiMAN HE-6se V2, HiFiMAN HE6 Remastered, HiFiMAN Susvara, 7 more.
553 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 Shure SE846: Zoom UAC-232 has +30 dB of headroom there against +26 dB. 4 dB is about 2.7 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for Focusrite Scarlett 16i16 (4th Gen) and Zoom UAC-232 because neither maker publishes no output noise figure.
| Headphone | Impedance | Needs | Focusrite Scarlett 16i16 (4th Gen) headroom | Zoom UAC-232 headroom | Focusrite Scarlett 16i16 (4th Gen) hiss | Zoom UAC-232 hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +26 dB damping | +30 dB damping | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +6 dB damping | +10 dB damping | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +16 dB damping | +21 dB damping | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +16 dB | +17 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +7 dB damping | +12 dB damping | not published | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +10 dB | +11 dB | not published | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +6 dB | +6 dB | not published | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | -1 dB damping | +3 dB damping | not published | not published |
The Focusrite Scarlett 16i16 (4th Gen) costs $11 more than the Zoom UAC-232, and on these three axes the money buys nothing: among the 567 models here there is not one that the Focusrite Scarlett 16i16 (4th Gen) handles and the Zoom UAC-232 does not — not on power, not on the one-eighth rule, not on hiss. The traffic runs the other way: the cheaper Zoom UAC-232 drives 10 models to 100 dB that the Focusrite Scarlett 16i16 (4th Gen) does not.
Only published figures count here; blank axes are counted separately.
Each in full: Focusrite Scarlett 16i16 (4th Gen) and Zoom UAC-232.