Both are audio interfaces, $599 against $599. 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 SSL 12 reaches 100 dB on 567 of the 567 models here, the Audient iD24 on 561.
| Specification | Audient iD24 | SSL 12 |
|---|---|---|
| Power into 32Ω | 119 mW | 1.2 W |
| Power into 150Ω | 80 mW | 252 mW |
| Power into 300Ω | 58 mW | 126 mW |
| Power into 600Ω | 52 mW | 63 mW |
| Output impedance | 50 Ω | 1 Ω |
| Output noise | not published | not published |
| Price | $599 | $599 |
| Headphones it reaches 100 dB on out of 567 | 561 | 567 |
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.
| Load | Audient iD24 | SSL 12 |
|---|---|---|
| 32 Ω | Derived | Upper bound |
| 150 Ω | Derived | Upper bound |
| 300 Ω | Derived | Upper bound |
| 600 Ω | Recomputed | Upper bound |
Neither column is a power rating, and the two are not even weak in the same way. The SSL 12 figures are ceilings worked out from a maximum output voltage, on the assumption that the amplifier holds it into the load. The Audient iD24 figures are worked out from figures its maker did publish — power at other loads, or the voltage printed beside it. The second method understates; the first flatters. That is the wrong way round for reading the table straight across, so a gap in favour of the SSL 12 is the one to doubt.
What each of these labels means, and why a derived figure is still worth printing, is set out in how this data was built.
6 headphones reach 100 dB on the SSL 12 but not on the Audient iD24 — Moondrop COSMO, Moondrop PARA, Symphonium Crimson, 3 more.
546 headphones are left alone by the SSL 12 under the one-eighth rule but coloured by the Audient iD24 (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Ocean, 543 more).
561 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.
The counts above say how many models the two treat differently. This says by how much. The same 8 headphones appear on every page of this kind, ordered from the easiest to drive to the hardest, so a row can be read across pages as well as across columns. Headroom is at a 100 dB SPL peak.
The widest gap on the list is the Shure SE846: SSL 12 has +39 dB of headroom there against +29 dB. 10 dB is about 9.5 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for Audient iD24 and SSL 12 because neither maker publishes no output noise figure. That is a gap in the specification, not a quiet amplifier, and it is left blank here rather than filled with a plausible number.
| Headphone | Impedance | Needs | Audient iD24 headroom | SSL 12 headroom | Audient iD24 hiss | SSL 12 hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +29 dB damping | +39 dB | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +9 dB damping | +19 dB | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +22 dB damping | +28 dB | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +20 dB damping | +24 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +11 dB damping | +21 dB | not published | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +15 dB | +17 dB | not published | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +9 dB damping | +13 dB | not published | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | +5 dB damping | +11 dB | not published | not published |
These two cost the same, $599, so price settles nothing. Out of the 567 models here, the SSL 12 drives 6 models to 100 dB and leaves 546 alone under the one-eighth rule — and on the other side there is no such advantage at all.
Everything in this paragraph counts only figures the two makers published. An advantage on an axis one of them leaves blank cannot be counted, and is not counted — how often that happens is its own page.
Each has a page of its own with every power figure traced to what the maker published and a full headphone list: Audient iD24 and SSL 12. Or put either against your own headphones in the source comparison tool.