Both are desktop DAC/amps, $449 against $520. 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?
On raw power they are level: each reaches 100 dB on 567 of the 567 non-electrostatic models here.
| Specification | JDS Labs Element III MK2 | SMSL DO400 |
|---|---|---|
| Power into 32Ω | 2.3 W | 3.0 W |
| Power into 150Ω | 584 mW | 938 mW |
| Power into 300Ω | 292 mW | 700 mW |
| Power into 600Ω | 146 mW | 350 mW |
| Output impedance | 0.7 Ω | <0.1 Ω |
| Output noise | 1.5 µV unverified | not published |
| Price | $449 | $520 |
| Headphones it reaches 100 dB on out of 567 | 567 | 567 |
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.
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 SMSL DO400 under the one-eighth rule but coloured by the JDS Labs Element III MK2 (Campfire Audio Chimera, Moondrop Armature Art 12, Softears Volume, 1 more).
567 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: JDS Labs Element III MK2 and SMSL DO400. Or put either against your own headphones in the source comparison tool.