Short answer
Both are audio interfaces, $432 against $599.
The SSL 12 reaches 100 dB on 567 of the 567 models here, the Roland Rubix44 on 542.
| Specification | Roland Rubix44 | SSL 12 |
|---|---|---|
| Power into 32Ω | 19 mW | 1.2 W |
| Power into 150Ω | 15 mW | 252 mW |
| Power into 300Ω | 9.4 mW | 126 mW |
| Power into 600Ω | 5.4 mW | 63 mW |
| Output impedance | 47 Ω | 1 Ω |
| Output noise | not published | not published |
| Price | $432 | $599 |
| Headphones it reaches 100 dB on out of 567 | 542 | 567 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Load | Roland Rubix44 | SSL 12 |
|---|---|---|
| 32 Ω | Derived | Upper bound |
| 150 Ω | Derived | Upper bound |
| 300 Ω | Derived | Upper bound |
| 600 Ω | Derived | 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 Roland Rubix44 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.
25 headphones reach 100 dB on the SSL 12 but not on the Roland Rubix44 — Audeze LCD-5, Dan Clark Audio AEON 2 Closed, Dan Clark Audio AEON 2 Noire, 22 more.
546 headphones are left alone by the SSL 12 under the one-eighth rule but coloured by the Roland Rubix44 (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Ocean, 543 more).
542 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 Shure SE846: SSL 12 has +39 dB of headroom there against +21 dB. 18 dB is about 61 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for Roland Rubix44 and SSL 12 because neither maker publishes no output noise figure.
| Headphone | Impedance | Needs | Roland Rubix44 headroom | SSL 12 headroom | Roland Rubix44 hiss | SSL 12 hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +21 dB damping | +39 dB | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +1 dB damping | +19 dB | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +13 dB damping | +28 dB | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +12 dB damping | +24 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +3 dB damping | +21 dB | not published | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +6 dB | +17 dB | not published | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +2 dB damping | +13 dB | not published | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | -4 dB damping | +11 dB | not published | not published |
The SSL 12 costs $167 more than the Roland Rubix44. Out of the 567 models here, that difference buys 25 more models driven to 100 dB and 546 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: Roland Rubix44 and SSL 12.