The Roland Rubix22 is an audio interface at $210. It delivers 19 mW into 32Ω and 9.4 mW into 300Ω, which ranks it 275 of 280 for raw power among the sources in this database.
Measured at 100 dB SPL it has comfortable headroom on 352 of the 567 dynamic and planar headphones catalogued here, enough but not generous on 163, only marginal on 27 and not enough power for 25. Power here is worked out from the one published figure and the published 47Ω output impedance, which is what actually governs this amplifier. Output noise is not published, so the hiss estimate cannot be run.
The manufacturer publishes 20 mW into 47Ω. Everything else in the table above is worked out from those figures, and this table says which is which.
Derivation holds output voltage steady between and beyond the published loads rather than output power, because that is what an amplifier actually does. The full method is written up here.
Source: roland.com.
| Load | Power | Status | How it was arrived at |
|---|---|---|---|
| 32 Ω | 19 mW | Derived | worked out from the published figure and the published output impedance, through the divider that impedance creates |
| 47 Ω | 20 mW | Published | the manufacturer publishes this figure at this exact load |
| 150 Ω | 15 mW | Derived | worked out from the published figure and the published output impedance, through the divider that impedance creates |
| 300 Ω | 9.4 mW | Derived | worked out from the published figure and the published output impedance, through the divider that impedance creates |
| 600 Ω | 5.4 mW | Derived | worked out from the published figure and the published output impedance, through the divider that impedance creates |
Ordered from easiest to hardest to drive. Headroom is measured at 100 dB SPL, which is louder than almost anyone listens — a small negative number means the source still plays loud, just without reserve for peaks.
These figures come from each manufacturer's own sensitivity rating. A handful of planars — the HiFiMAN Susvara and the Abyss AB-1266 in particular — are widely reported to need far more than their published sensitivity implies, so treat a bare pass on those as optimistic rather than settled.
| Headphone | Impedance | Sensitivity | Needs | Headroom | Verdict |
|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 114.0 dB/mW | 0.04 mW | +21 dB | Comfortable damping |
| 64 Audio U12t | 12.6 Ω | 108.0 dB/mW | 0.16 mW | +17 dB | Comfortable damping |
| Shure SE215 | 17 Ω | 107.0 dB/mW | 0.20 mW | +17 dB | Comfortable damping |
| Moondrop Aria | 32 Ω | 107.1 dB/mW | 0.19 mW | +20 dB | Comfortable damping |
| Audeze LCD-X 2021 | 20 Ω | 103.0 dB/mW | 0.50 mW | +14 dB | Comfortable damping |
| Truthear Hexa | 20.5 Ω | 103.1 dB/mW | 0.49 mW | +14 dB | Comfortable damping |
| Sennheiser IE 200 | 18 Ω | 101.6 dB/mW | 0.69 mW | +12 dB | Comfortable damping |
| Sony MDR-7506 | 63 Ω | 106.0 dB/mW | 0.25 mW | +18 dB | Comfortable damping |
| Meze 99 Classics | 32 Ω | 103.0 dB/mW | 0.50 mW | +16 dB | Comfortable damping |
| Focal Clear MG | 55 Ω | 104.0 dB/mW | 0.40 mW | +17 dB | Comfortable damping |
| Philips SHP9500 | 32 Ω | 101.0 dB | 0.79 mW | +14 dB | Comfortable damping |
| Focal Utopia | 80 Ω | 104.0 dB/mW | 0.40 mW | +16 dB | Comfortable damping |
| Meze Empyrean | 32 Ω | 100.0 dB | 1.0 mW | +13 dB | Comfortable damping |
| Campfire Audio Andromeda 2020 | 9 Ω | 94.0 dB | 4.0 mW | +1 dB | Marginal damping |
| Etymotic ER2SE | 15 Ω | 96.0 dB/mW | 2.5 mW | +6 dB | Enough damping |
| AKG K371 | 32 Ω | 99.1 dB/mW | 1.2 mW | +12 dB | Comfortable damping |
| Audio-Technica ATH-M50X | 38 Ω | 99.0 dB/mW | 1.3 mW | +12 dB | Comfortable damping |
| Beyerdynamic DT 900 Pro X | 48 Ω | 100.0 dB/mW | 1.0 mW | +13 dB | Comfortable damping |
| Audeze LCD-2 Classic | 70 Ω | 101.0 dB/mW | 0.79 mW | +13 dB | Comfortable damping |
| Grado SR80x | 38 Ω | 98.0 dB/mW | 1.6 mW | +11 dB | Comfortable damping |
| Sennheiser HD 560S | 120 Ω | 100.8 dB/mW | 0.83 mW | +12 dB | Comfortable damping |
| HiFiMAN Edition XS | 18 Ω | 92.0 dB | 6.3 mW | +2 dB | Marginal damping |
| HiFiMAN Arya Stealth | 32 Ω | 94.0 dB | 4.0 mW | +7 dB | Enough damping |
| Dan Clark Audio AEON 2 Closed | 13 Ω | 90.0 dB/mW | 10 mW | -1 dB | Not enough damping |
| Audeze LCD-5 | 14 Ω | 90.0 dB/mW | 10 mW | -1 dB | Not enough damping |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 102.0 dB/mW | 0.63 mW | +12 dB | Comfortable damping |
| HiFiMAN HE400se | 25 Ω | 91.0 dB | 7.9 mW | +3 dB | Marginal damping |
| HiFiMAN Sundara | 32 Ω | 92.0 dB | 6.3 mW | +5 dB | Enough damping |
| Dan Clark Audio Stealth | 23 Ω | 90.0 dB/mW | 10 mW | +1 dB | Marginal damping |
| Fostex T50RP MK3 | 50 Ω | 92.0 dB/mW | 6.3 mW | +5 dB | Enough damping |
| AKG K702 | 62 Ω | 92.9 dB/mW | 5.1 mW | +5 dB | Enough damping |
| ZMF Verite Closed | 300 Ω | 99.0 dB/mW | 1.3 mW | +9 dB | Enough damping |
| Sennheiser HD 650 | 300 Ω | 97.8 dB/mW | 1.7 mW | +8 dB | Enough damping |
| Sennheiser HD 800S | 300 Ω | 96.8 dB/mW | 2.1 mW | +7 dB | Enough damping |
| Beyerdynamic DT 770 Pro (250Ω) | 250 Ω | 96.0 dB | 2.5 mW | +6 dB | Enough damping |
| Audio-Technica ATH-R70X | 470 Ω | 98.0 dB/mW | 1.6 mW | +6 dB | Enough |
| ZMF Atrium | 300 Ω | 96.0 dB/mW | 2.5 mW | +6 dB | Enough damping |
| Abyss AB-1266 Phi TC | 50 Ω | 88.0 dB/mW | 16 mW | +1 dB | Marginal damping |
| Sennheiser HD 600 | 300 Ω | 91.8 dB/mW | 6.6 mW | +2 dB | Marginal damping |
| HiFiMAN Susvara | 60 Ω | 83.0 dB | 50 mW | -4 dB | Not enough damping |
The manufacturer does not publish an output noise figure for this source, so the hiss estimate that runs on every other page here cannot be run on this one. Rather than substitute a plausible number, this page leaves the question open.
If you know the noise figure from a measurement you trust, the hiss calculator takes it directly and tells you where that noise lands in your own in-ears.
At 47Ω output impedance, the one-eighth rule says this source suits headphones of 376.0Ω and above. 561 of the 567 models here fall below that. That is most of the database, not a niche — 222 of them multi-driver in-ears, and the mismatch tilts the frequency response audibly rather than subtly.
The rule is a rule of thumb, not physics: a source impedance below one eighth of the headphone's keeps the interaction under about 1 dB. The checker works it out for any pair.
| Product | Price |
|---|---|
| Roland Rubix22 | $210 |
| Roland Rubix44 | $432 |
On every figure Roland publishes for this headphone output, the Roland Rubix22 is identical to the Roland Rubix44. Each of them states power at 47 Ω and an output impedance of 47 Ω — and each states the same values.
They do not cost the same. The spread across the 2 of them is $222, 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 |
| iFi GO link | USB dongle | $59 | 14 mW | 0.4 Ω | not published |
Of the 280 sources here, 38 do everything the Roland Rubix22 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 $210 — $181 less, and a USB dongle rather than an audio interface.
The cheaper one also publishes a noise figure, which the Roland Rubix22 does not — so on the paperwork it is ahead, not merely level.
This counts a headphone output and nothing else. Inputs, converters, microphone preamps, balanced outputs, the volume control, the case and the warranty are all outside it, and any of them can be the reason to buy the dearer box. What the count does say is that the three numbers a maker can be held to do not separate them.
$219 · 333 mW into 32Ω · output Ω not published
Compare →$200 · 30 mW into 32Ω · 10 Ω out
Compare →$199 · 31 mW into 32Ω · 50 Ω out
Compare →$199 · 112 mW into 32Ω · output Ω not published
Compare →$199 · 84 mW into 32Ω · output Ω not published
Compare →$199 · 12 mW into 32Ω · output Ω not published
Compare →Worked out in advance against its closest rivals: vs Apogee BOOM · vs M-Audio AIR 192|14 · vs MOTU M2 · vs Roland BRIDGE CAST · vs SSL 2 MkII · vs Zoom AMS-44. Each of those pages lists the headphones that tell the two apart.
Or put any two side by side in the source comparison tool, or run your own headphones through the amplifier matcher. Or see every Roland source in the database, and how much of what this site says about them came from Roland’s own documents.