The RME Fireface UFX II is an audio interface at $2799. It delivers 200 mW into 32Ω and 21 mW into 300Ω, which ranks it 160 of 280 for raw power among the sources in this database.
Measured at 100 dB SPL it has comfortable headroom on 530 of the 567 dynamic and planar headphones catalogued here, enough but not generous on 31, only marginal on 3 and not enough power for 3. Power is published at 32Ω; the rest of the table is derived from those figures. Output noise is not published, so the hiss estimate cannot be run.
The manufacturer publishes 200 mW into 32Ω. The rest of the table is worked out from those.
Derived rows hold output voltage steady, as an amplifier does (method).
Source: rme-audio.de.
| Load | Power | Status | How it was arrived at |
|---|---|---|---|
| 32 Ω | 200 mW | Published | the manufacturer publishes this figure at this exact load |
| 150 Ω | 43 mW | Derived | beyond the published loads, holding output voltage constant — which understates rather than flatters |
| 300 Ω | 21 mW | Derived | beyond the published loads, holding output voltage constant — which understates rather than flatters |
| 600 Ω | 11 mW | Derived | beyond the published loads, holding output voltage constant — which understates rather than flatters |
Easiest to hardest to drive, with headroom at a 100 dB SPL peak.
| Headphone | Impedance | Sensitivity | Needs | Headroom | Verdict |
|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 114.0 dB/mW | 0.04 mW | +32 dB | Comfortable damping |
| 64 Audio U12t | 12.6 Ω | 108.0 dB/mW | 0.16 mW | +27 dB | Comfortable damping |
| Shure SE215 | 17 Ω | 107.0 dB/mW | 0.20 mW | +27 dB | Comfortable |
| Moondrop Aria | 32 Ω | 107.1 dB/mW | 0.19 mW | +30 dB | Comfortable |
| Audeze LCD-X 2021 | 20 Ω | 103.0 dB/mW | 0.50 mW | +24 dB | Comfortable |
| Truthear Hexa | 20.5 Ω | 103.1 dB/mW | 0.49 mW | +24 dB | Comfortable |
| Sennheiser IE 200 | 18 Ω | 101.6 dB/mW | 0.69 mW | +22 dB | Comfortable |
| Sony MDR-7506 | 63 Ω | 106.0 dB/mW | 0.25 mW | +26 dB | Comfortable |
| Meze 99 Classics | 32 Ω | 103.0 dB/mW | 0.50 mW | +26 dB | Comfortable |
| Focal Clear MG | 55 Ω | 104.0 dB/mW | 0.40 mW | +25 dB | Comfortable |
| Philips SHP9500 | 32 Ω | 101.0 dB | 0.79 mW | +24 dB | Comfortable |
| Focal Utopia | 80 Ω | 104.0 dB/mW | 0.40 mW | +23 dB | Comfortable |
| Meze Empyrean | 32 Ω | 100.0 dB | 1.0 mW | +23 dB | Comfortable |
| Campfire Audio Andromeda 2020 | 9 Ω | 94.0 dB | 4.0 mW | +12 dB | Comfortable damping |
| Etymotic ER2SE | 15 Ω | 96.0 dB/mW | 2.5 mW | +16 dB | Comfortable damping |
| AKG K371 | 32 Ω | 99.1 dB/mW | 1.2 mW | +22 dB | Comfortable |
| Audio-Technica ATH-M50X | 38 Ω | 99.0 dB/mW | 1.3 mW | +21 dB | Comfortable |
| Beyerdynamic DT 900 Pro X | 48 Ω | 100.0 dB/mW | 1.0 mW | +21 dB | Comfortable |
| Audeze LCD-2 Classic | 70 Ω | 101.0 dB/mW | 0.79 mW | +21 dB | Comfortable |
| Grado SR80x | 38 Ω | 98.0 dB/mW | 1.6 mW | +20 dB | Comfortable |
| Sennheiser HD 560S | 120 Ω | 100.8 dB/mW | 0.83 mW | +18 dB | Comfortable |
| HiFiMAN Edition XS | 18 Ω | 92.0 dB | 6.3 mW | +13 dB | Comfortable |
| HiFiMAN Arya Stealth | 32 Ω | 94.0 dB | 4.0 mW | +17 dB | Comfortable |
| Dan Clark Audio AEON 2 Closed | 13 Ω | 90.0 dB/mW | 10 mW | +9 dB | Enough damping |
| Audeze LCD-5 | 14 Ω | 90.0 dB/mW | 10 mW | +9 dB | Enough damping |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 102.0 dB/mW | 0.63 mW | +16 dB | Comfortable |
| HiFiMAN HE400se | 25 Ω | 91.0 dB | 7.9 mW | +13 dB | Comfortable |
| HiFiMAN Sundara | 32 Ω | 92.0 dB | 6.3 mW | +15 dB | Comfortable |
| Dan Clark Audio Stealth | 23 Ω | 90.0 dB/mW | 10 mW | +12 dB | Comfortable |
| Fostex T50RP MK3 | 50 Ω | 92.0 dB/mW | 6.3 mW | +13 dB | Comfortable |
| AKG K702 | 62 Ω | 92.9 dB/mW | 5.1 mW | +13 dB | Comfortable |
| ZMF Verite Closed | 300 Ω | 99.0 dB/mW | 1.3 mW | +12 dB | Comfortable |
| Sennheiser HD 650 | 300 Ω | 97.8 dB/mW | 1.7 mW | +11 dB | Comfortable |
| Sennheiser HD 800S | 300 Ω | 96.8 dB/mW | 2.1 mW | +10 dB | Comfortable |
| Beyerdynamic DT 770 Pro (250Ω) | 250 Ω | 96.0 dB | 2.5 mW | +10 dB | Comfortable |
| Audio-Technica ATH-R70X | 470 Ω | 98.0 dB/mW | 1.6 mW | +9 dB | Enough |
| ZMF Atrium | 300 Ω | 96.0 dB/mW | 2.5 mW | +9 dB | Enough |
| Abyss AB-1266 Phi TC | 50 Ω | 88.0 dB/mW | 16 mW | +9 dB | Enough |
| Sennheiser HD 600 | 300 Ω | 91.8 dB/mW | 6.6 mW | +5 dB | Enough |
| HiFiMAN Susvara | 60 Ω | 83.0 dB | 50 mW | +3 dB | Enough |
The manufacturer does not publish an output noise figure for this source, so there is no hiss estimate here. If you have a measured figure, the hiss calculator takes it.
At 2Ω output impedance, the one-eighth rule says this source suits headphones of 16.0Ω and above. 89 of the 567 models here fall below that. Most of them are multi-driver in-ears, and the mismatch tilts the frequency response audibly rather than subtly.
| Product | Price |
|---|---|
| RME Fireface UFX II | $2799 |
| RME Fireface UFX III | $3199 |
On every figure RME publishes for this headphone output, the RME Fireface UFX II is identical to the RME Fireface UFX III. Each of them states power at 32 Ω and an output impedance of 2 Ω — and each states the same values.
They do not cost the same. The spread across the 2 of them is $400, and none of that difference is visible in the figures above.
Identical published figures do not mean identical products. A spec sheet for a headphone output covers power, output impedance and noise. It says nothing about the converter, the inputs, the case, the battery, the volume control or how any of it sounds, and those are real differences that cost real money. What this section says is narrower and worth saying anyway: if you are choosing between these on what the maker printed about the headphone jack, there is nothing to choose.
15 groups of products in this database share a spec sheet this way, 36 products in all.
| Source | Type | Price | Into 300 Ω | Output impedance | Output noise |
|---|---|---|---|---|---|
| FiiO KA11 | USB dongle | $29 | 22 mW | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | Bluetooth receiver | $59 | 10.0 mW | 0.6 Ω | 1.0 µV |
| FiiO KA3 | USB dongle | $79 | 14 mW | 0.5 Ω | 1.7 µV |
Of the 280 sources here, 104 do everything the RME Fireface UFX II does as a headphone output: reach 100 dB on every headphone it reaches and stay inside the one-eighth rule wherever it does. The cheapest of them is the FiiO KA11 at $29, against this one’s $2799 — $2770 less, and a USB dongle rather than an audio interface.
The cheaper one also publishes a noise figure, which the RME Fireface UFX II does not — so on the paperwork it is ahead, not merely level.
This counts the headphone output only; inputs, converters, the volume control and the build are outside it.
$2790 · 961 mW into 32Ω · 0.035 Ω out
Compare →$2499 · 1.9 W into 32Ω · 0.1 Ω out
Compare →$3199 · 200 mW into 32Ω · 2 Ω out
Compare →$2199 · 3.0 W into 32Ω · 0.1 Ω out
Compare →$3499 · 1.3 W into 32Ω · output Ω not published
Compare →$3500 · 986 mW into 32Ω · 10 Ω out
Compare →Compared with its closest rivals: vs Audient Horizon 8P · vs Audient ORIA · vs Lynx Aurora(n) · vs Merging Anubis · vs RME ADI-2 DAC FS · vs RME ADI-2 Pro EX · vs RME ADI-2 Pro FS R · vs RME Babyface Pro FS · vs RME Fireface UCX II.