Short answer
Both are audio interfaces, $599 against $400.
The Arturia AudioFuse Rev2 reaches 100 dB on 564 of the 567 models here, the IK Multimedia AXE I/O on 561.
| Specification | Arturia AudioFuse Rev2 | IK Multimedia AXE I/O |
|---|---|---|
| Power into 32Ω | 187 mW | 115 mW |
| Power into 150Ω | 40 mW | 60 mW |
| Power into 300Ω | 20 mW | 30 mW |
| Power into 600Ω | 10.0 mW | 15 mW |
| Output impedance | 33 Ω | <0.1 Ω |
| Output noise | not published | not published |
| Price | $599 | $400 |
| Headphones it reaches 100 dB on out of 567 | 564 | 561 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Load | Arturia AudioFuse Rev2 | IK Multimedia AXE I/O |
|---|---|---|
| 32 Ω | Upper bound | Derived |
| 150 Ω | Upper bound | Derived |
| 300 Ω | Upper bound | Derived |
| 600 Ω | Upper bound | Derived |
Neither column is a power rating, and the two are not even weak in the same way. The Arturia AudioFuse Rev2 figures are ceilings worked out from a maximum output voltage, on the assumption that the amplifier holds it into the load. The IK Multimedia AXE I/O 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 Arturia AudioFuse Rev2 is the one to doubt.
3 headphones reach 100 dB on the Arturia AudioFuse Rev2 but not on the IK Multimedia AXE I/O — Moondrop COSMO, Symphonium Helios, Symphonium Zenith.
545 headphones are left alone by the IK Multimedia AXE I/O under the one-eighth rule but coloured by the Arturia AudioFuse Rev2 (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Nio, 542 more).
561 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: Arturia AudioFuse Rev2 has +31 dB of headroom there against +29 dB. 2 dB is about 1.6 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for Arturia AudioFuse Rev2 and IK Multimedia AXE I/O because neither maker publishes no output noise figure.
| Headphone | Impedance | Needs | Arturia AudioFuse Rev2 headroom | IK Multimedia AXE I/O headroom | Arturia AudioFuse Rev2 hiss | IK Multimedia AXE I/O hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +31 dB damping | +29 dB | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +11 dB damping | +9 dB | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +20 dB damping | +22 dB | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +16 dB damping | +18 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +13 dB damping | +11 dB | not published | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +9 dB | +11 dB | not published | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +5 dB | +7 dB | not published | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | +3 dB damping | +5 dB | not published | not published |
The Arturia AudioFuse Rev2 costs $199 more than the IK Multimedia AXE I/O. Out of the 567 models here, that difference buys 3 more models driven to 100 dB.
It does not run one way only: the cheaper IK Multimedia AXE I/O leaves 545 models alone under the one-eighth rule that the Arturia AudioFuse Rev2 does not, which is the part worth checking against your own headphones before paying the difference.
Only published figures count here; blank axes are counted separately.
Each in full: Arturia AudioFuse Rev2 and IK Multimedia AXE I/O.