Both are audio interfaces, $2499 against $1749. 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 RME ADI-2 Pro EX reaches 100 dB on 567 of the 567 models here, the RME Fireface UCX II on 564.
| Specification | RME ADI-2 Pro EX | RME Fireface UCX II |
|---|---|---|
| Power into 32Ω | 1.9 W | 210 mW |
| Power into 150Ω | 540 mW | 45 mW |
| Power into 300Ω | 370 mW | 22 mW |
| Power into 600Ω | 185 mW | 11 mW |
| Output impedance | 0.1 Ω | 1 Ω |
| Output noise | 2.18 µV | not published |
| Price | $2499 | $1749 |
| Headphones it reaches 100 dB on out of 567 | 567 | 564 |
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 | RME ADI-2 Pro EX | RME Fireface UCX II |
|---|---|---|
| 32 Ω | Published | Published |
| 150 Ω | Derived | Derived |
| 300 Ω | Published | Derived |
| 600 Ω | Derived | Derived |
Both makers publish a power rating, which is less common than the table above makes it look: of the 280 sources here, 209 publish a figure at at least one load and only 2 publish one at all four. RME ADI-2 Pro EX publishes at 32 Ω and at 300 Ω; RME Fireface UCX II at 32 Ω. Every other row is worked out from those — between two published loads, or beyond them holding voltage constant, which understates rather than flatters.
So the two columns are not equally firm row by row: at 300 Ω only the RME ADI-2 Pro EX figure is the maker’s own. On those rows the derived number is the one to doubt first.
What each of these labels means, and why a derived figure is still worth printing, is set out in how this data was built.
3 headphones reach 100 dB on the RME ADI-2 Pro EX but not on the RME Fireface UCX II — Moondrop PARA, Symphonium Crimson, Symphonium Titan.
15 headphones are left alone by the RME ADI-2 Pro EX under the one-eighth rule but coloured by the RME Fireface UCX II (64 Audio Nio, 64 Audio Volur, Campfire Audio Andromeda 2023, 12 more).
564 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 Campfire Audio Andromeda 2020: RME ADI-2 Pro EX has +25 dB of headroom there against +12 dB. 13 dB is about 20 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for RME Fireface UCX II because that 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 | RME ADI-2 Pro EX headroom | RME Fireface UCX II headroom | RME ADI-2 Pro EX hiss | RME Fireface UCX II hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +45 dB | +32 dB | 21 dB | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +25 dB | +12 dB | 1 dB | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +31 dB | +21 dB | -1 dB | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +28 dB | +16 dB | -5 dB | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +24 dB | +13 dB | -6 dB | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +22 dB | +10 dB | -12 dB | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +17 dB | +5 dB | -16 dB | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | +13 dB | +3 dB | -18 dB | not published |
The RME ADI-2 Pro EX costs $750 more than the RME Fireface UCX II. Out of the 567 models here, that difference buys 3 more models driven to 100 dB and 15 more models left alone under the one-eighth rule.
Nothing runs the other way: there is no axis here on which the cheaper of the two does better.
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: RME ADI-2 Pro EX and RME Fireface UCX II. Or put either against your own headphones in the source comparison tool.