Both are desktop amplifiers, $100 against $99. This page puts them side by side on the only three things a maker can be held to — power, output impedance and noise — and then asks the question that actually matters: which headphones do they treat differently?
The JDS Labs Atom+ (2nd gen) reaches 100 dB on 566 of the 567 models here, the Fosi Audio SK02 on 564.
| Specification | Fosi Audio SK02 | JDS Labs Atom+ (2nd gen) |
|---|---|---|
| Power into 32Ω | 190 mW | 1.0 W |
| Power into 150Ω | 41 mW | 545 mW |
| Power into 300Ω | 20 mW | 272 mW |
| Power into 600Ω | 10 mW | 136 mW |
| Output impedance | not published | 0.7 Ω |
| Output noise | not published | 1.99 µV |
| Price | $100 | $99 |
| Headphones it reaches 100 dB on out of 567 | 564 | 566 |
A figure marked not published is missing from the maker’s own material, which is not the same as being good or bad. Where one of these two publishes a number and the other does not, the comparison on that axis cannot be made at all — and saying so is more useful than guessing.
2 headphones reach 100 dB on the JDS Labs Atom+ (2nd gen) but not on the Fosi Audio SK02 — Moondrop PARA, Symphonium Crimson.
564 of the 567 models here reach 100 dB on both. That is a power count and nothing more; whether either source suits a given headphone also depends on the two lines above.
Each has a page of its own with every power figure traced to what the maker published and a full headphone list: Fosi Audio SK02 and JDS Labs Atom+ (2nd gen). Or put either against your own headphones in the source comparison tool.