Short answer
Both are audio interfaces, $210 against $229.
The SSL 2 MkII reaches 100 dB on 565 of the 567 models here, the Roland Rubix22 on 542.
| Specification | Roland Rubix22 | SSL 2 MkII |
|---|---|---|
| Power into 32Ω | 19 mW | 374 mW |
| Power into 150Ω | 15 mW | 80 mW |
| Power into 300Ω | 9.4 mW | 40 mW |
| Power into 600Ω | 5.4 mW | 20 mW |
| Output impedance | 47 Ω | 1 Ω |
| Output noise | not published | not published |
| Price | $210 | $229 |
| Headphones it reaches 100 dB on out of 567 | 542 | 565 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Load | Roland Rubix22 | SSL 2 MkII |
|---|---|---|
| 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 2 MkII figures are ceilings worked out from a maximum output voltage, on the assumption that the amplifier holds it into the load. The Roland Rubix22 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 2 MkII is the one to doubt.
23 headphones reach 100 dB on the SSL 2 MkII but not on the Roland Rubix22 — Audeze LCD-5, Dan Clark Audio AEON 2 Closed, Dan Clark Audio AEON 2 Noire, 20 more.
546 headphones are left alone by the SSL 2 MkII under the one-eighth rule but coloured by the Roland Rubix22 (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 Campfire Audio Andromeda 2020: SSL 2 MkII has +14 dB of headroom there against +1 dB. 13 dB is about 19 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for Roland Rubix22 and SSL 2 MkII because neither maker publishes no output noise figure.
| Headphone | Impedance | Needs | Roland Rubix22 headroom | SSL 2 MkII headroom | Roland Rubix22 hiss | SSL 2 MkII hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +21 dB damping | +34 dB | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +1 dB damping | +14 dB | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +13 dB damping | +23 dB | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +12 dB damping | +19 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +3 dB damping | +16 dB | not published | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +6 dB | +12 dB | not published | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +2 dB damping | +8 dB | not published | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | -4 dB damping | +6 dB | not published | not published |
The SSL 2 MkII costs $19 more than the Roland Rubix22. Out of the 567 models here, that difference buys 23 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 Rubix22 and SSL 2 MkII.