Short answer
Both are desktop amplifiers, $129 against $119.
On raw power they are level: each reaches 100 dB on 567 of the 567 non-electrostatic models here.
| Specification | JDS Labs Atom Amp 2 | Schiit Magni Unity |
|---|---|---|
| Power into 32Ω | 2.6 W | 2.5 W |
| Power into 150Ω | 567 mW | 622 mW |
| Power into 300Ω | 284 mW | 415 mW |
| Power into 600Ω | 143 mW | 220 mW |
| Output impedance | 0.7 Ω | 0.1 Ω |
| Output noise | 1.33 µV | 1.59 µV |
| Price | $129 | $119 |
| Headphones it reaches 100 dB on out of 567 | 567 | 567 |
| Load | JDS Labs Atom Amp 2 | Schiit Magni Unity |
|---|---|---|
| 32 Ω | Published | Published |
| 150 Ω | Derived | Derived |
| 300 Ω | Derived | Published |
| 600 Ω | Published | Published |
Both makers publish a power rating. JDS Labs Atom Amp 2 publishes at 32 Ω and at 600 Ω; Schiit Magni Unity at 32 Ω, at 300 Ω and at 600 Ω. The other rows are worked out from those.
So the two columns are not equally firm row by row: at 300 Ω only the Schiit Magni Unity figure is the maker’s own. On those rows the derived number is the one to doubt first.
On power they are interchangeable across this whole database: there is no headphone here that one reaches 100 dB on and the other does not.
4 headphones are left alone by the Schiit Magni Unity under the one-eighth rule but coloured by the JDS Labs Atom Amp 2 (Campfire Audio Chimera, Moondrop Armature Art 12, Softears Volume, 1 more).
567 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: Schiit Magni Unity has +46 dB of headroom there against +43 dB. 4 dB is about 2.3 times the power, which matters for peaks rather than for how loud the music sits.
Hiss below about 20 dB SPL is inaudible in a quiet room.
| Headphone | Impedance | Needs | JDS Labs Atom Amp 2 headroom | Schiit Magni Unity headroom | JDS Labs Atom Amp 2 hiss | Schiit Magni Unity hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +43 dB | +46 dB | 17 dB | 18 dB |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +23 dB | +26 dB | -3 dB | -2 dB |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +32 dB | +31 dB | -5 dB | -3 dB |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +27 dB | +29 dB | -10 dB | -8 dB |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +24 dB | +25 dB | -11 dB | -9 dB |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +21 dB | +22 dB | -16 dB | -15 dB |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +16 dB | +18 dB | -20 dB | -19 dB |
| HiFiMAN Susvara | 60 Ω | 50 mW | +15 dB | +14 dB | -22 dB | -21 dB |
The JDS Labs Atom Amp 2 costs $10 more than the Schiit Magni Unity, and on these three axes the money buys nothing: among the 567 models here there is not one that the JDS Labs Atom Amp 2 handles and the Schiit Magni Unity does not — not on power, not on the one-eighth rule, not on hiss. The traffic runs the other way: the cheaper Schiit Magni Unity leaves 4 models alone under the one-eighth rule that the JDS Labs Atom Amp 2 does not.
Only published figures count here; blank axes are counted separately.
Each in full: JDS Labs Atom Amp 2 and Schiit Magni Unity.