Short answer
Both are audio interfaces, $299 against $399.
The Apogee BOOM reaches 100 dB on 565 of the 567 models here, the Zoom UAC-232 on 563.
| Specification | Apogee BOOM | Zoom UAC-232 |
|---|---|---|
| Power into 32Ω | 240 mW | 148 mW |
| Power into 150Ω | 51 mW | 51 mW |
| Power into 300Ω | 26 mW | 28 mW |
| Power into 600Ω | 13 mW | 14 mW |
| Output impedance | 0.5 Ω | 12 Ω |
| Output noise | not published | not published |
| Price | $299 | $399 |
| Headphones it reaches 100 dB on out of 567 | 565 | 563 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Load | Apogee BOOM | Zoom UAC-232 |
|---|---|---|
| 32 Ω | Published | Derived |
| 150 Ω | Derived | Derived |
| 300 Ω | Derived | Derived |
| 600 Ω | Derived | Derived |
Only one of these two columns starts from a power rating. Apogee BOOM publishes one at 32 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 32 Ω is the only load here at which its maker can be held to a figure.
2 headphones reach 100 dB on the Apogee BOOM but not on the Zoom UAC-232 — Symphonium Crimson, Symphonium Helios.
519 headphones are left alone by the Apogee BOOM under the one-eighth rule but coloured by the Zoom UAC-232 (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Nio, 516 more).
563 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 HiFiMAN HE400se: Apogee BOOM has +14 dB of headroom there against +12 dB. 2 dB is about 1.6 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for Apogee BOOM and Zoom UAC-232 because neither maker publishes no output noise figure.
| Headphone | Impedance | Needs | Apogee BOOM headroom | Zoom UAC-232 headroom | Apogee BOOM hiss | Zoom UAC-232 hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +32 dB | +30 dB damping | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +12 dB | +10 dB damping | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +21 dB | +21 dB damping | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +17 dB | +17 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +14 dB | +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 | +4 dB | +3 dB damping | not published | not published |
The Zoom UAC-232 costs $100 more than the Apogee BOOM, and on these three axes the money buys nothing: among the 567 models here there is not one that the Zoom UAC-232 handles and the Apogee BOOM does not — not on power, not on the one-eighth rule, not on hiss. The traffic runs the other way: the cheaper Apogee BOOM drives 2 models to 100 dB and leaves 519 alone under the one-eighth rule that the Zoom UAC-232 does not.
Only published figures count here; blank axes are counted separately.
Each in full: Apogee BOOM and Zoom UAC-232.