Short answer
Both are audio interfaces, $2790 against $1749.
The Merging Anubis reaches 100 dB on 566 of the 567 models here, the RME Fireface UCX II on 564.
| Specification | Merging Anubis | RME Fireface UCX II |
|---|---|---|
| Power into 32Ω | 961 mW | 210 mW |
| Power into 150Ω | 205 mW | 45 mW |
| Power into 300Ω | 103 mW | 22 mW |
| Power into 600Ω | 51 mW | 11 mW |
| Output impedance | 0.035 Ω | 1 Ω |
| Output noise | not published | not published |
| Price | $2790 | $1749 |
| Headphones it reaches 100 dB on out of 567 | 566 | 564 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Load | Merging Anubis | RME Fireface UCX II |
|---|---|---|
| 32 Ω | Upper bound | Published |
| 150 Ω | Upper bound | Derived |
| 300 Ω | Upper bound | Derived |
| 600 Ω | Upper bound | Derived |
These two columns are not the same kind of number, and that matters more than the gap between them. RME Fireface UCX II publishes a power rating (at 32 Ω); Merging Anubis publishes no power figure at any load, only a maximum output voltage, so every milliwatt in its column is a ceiling worked out from that voltage.
A ceiling assumes the amplifier holds that voltage into the load, and nothing on Merging Anubis’s own sheet says it does. It is the most flattering reading available, and it is used here only because the alternative is a blank. Where the Merging Anubis column looks the stronger of the two, treat the difference as unproven rather than measured. 24 of the 280 sources here are in that position, with no published power rating at any load.
2 headphones reach 100 dB on the Merging Anubis but not on the RME Fireface UCX II — Moondrop PARA, Symphonium Crimson.
15 headphones are left alone by the Merging Anubis 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.
Headroom is at a 100 dB SPL peak.
The widest gap on the list is the Sennheiser HD 600: Merging Anubis has +12 dB of headroom there against +5 dB. 7 dB is about 4.6 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for Merging Anubis and RME Fireface UCX II because neither maker publishes no output noise figure.
| Headphone | Impedance | Needs | Merging Anubis headroom | RME Fireface UCX II headroom | Merging Anubis hiss | RME Fireface UCX II hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +38 dB | +32 dB | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +18 dB | +12 dB | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +27 dB | +21 dB | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +23 dB | +16 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +20 dB | +13 dB | not published | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +16 dB | +10 dB | not published | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +12 dB | +5 dB | not published | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | +10 dB | +3 dB | not published | not published |
The Merging Anubis costs $1041 more than the RME Fireface UCX II. Out of the 567 models here, that difference buys 2 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.
Only published figures count here; blank axes are counted separately.
Each in full: Merging Anubis and RME Fireface UCX II.