Short answer
Both are audio interfaces, $809 against $720.
The Audient iD44 MkII reaches 100 dB on 565 of the 567 models here, the Audient NERO on 559.
| Specification | Audient iD44 MkII | Audient NERO |
|---|---|---|
| Power into 32Ω | 190 mW | 86 mW |
| Power into 150Ω | 40 mW | 23 mW |
| Power into 300Ω | 42 mW | 13 mW |
| Power into 600Ω | 54 mW | 7.4 mW |
| Output impedance | 50 Ω | not published |
| Output noise | not published | not published |
| Price | $809 | $720 |
| Headphones it reaches 100 dB on out of 567 | 565 | 559 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Load | Audient iD44 MkII | Audient NERO |
|---|---|---|
| 32 Ω | Derived | Derived |
| 150 Ω | Derived | Derived |
| 300 Ω | Derived | Derived |
| 600 Ω | Published | Published |
Both makers publish a power rating. Audient iD44 MkII publishes at 600 Ω; Audient NERO at 600 Ω. The other rows are worked out from those.
The two publish at the same loads, which is the one case where the rows of this table can be read straight across.
6 headphones reach 100 dB on the Audient iD44 MkII but not on the Audient NERO — Moondrop COSMO, Moondrop PARA 2, Moondrop VENUS, 3 more.
559 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 Audio-Technica ATH-R70X: Audient iD44 MkII has +15 dB of headroom there against +7 dB. 7 dB is about 5.5 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for Audient iD44 MkII and Audient NERO because neither maker publishes no output noise figure.
| Headphone | Impedance | Needs | Audient iD44 MkII headroom | Audient NERO headroom | Audient iD44 MkII hiss | Audient NERO hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +32 dB damping | +28 dB | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +12 dB damping | +8 dB | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +18 dB damping | +18 dB | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +18 dB damping | +14 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +13 dB damping | +10 dB | not published | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +15 dB | +7 dB | not published | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +8 dB damping | +3 dB | not published | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | +0 dB damping | +0 dB | not published | not published |
The Audient iD44 MkII costs $89 more than the Audient NERO. Out of the 567 models here, that difference buys 6 more models driven to 100 dB.
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: Audient iD44 MkII and Audient NERO.