Both are portable players, $800 against $649. 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 565 of the 567 non-electrostatic models here.
| Specification | Astell&Kern SR35 | Cayin N3 Ultra |
|---|---|---|
| Power into 32Ω | 300 mW | 250 mW |
| Power into 150Ω | 64 mW | 53 mW |
| Power into 300Ω | 32 mW | 27 mW |
| Power into 600Ω | 16 mW | 13 mW |
| Output impedance | 1.1 Ω | 0.5 Ω |
| Output noise | 4 µV unverified | not published |
| Price | $800 | $649 |
| Headphones it reaches 100 dB on out of 567 | 565 | 565 |
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.
27 headphones are left alone by the Cayin N3 Ultra under the one-eighth rule but coloured by the Astell&Kern SR35 (64 Audio Nio, 64 Audio U18s, 64 Audio Volur, 24 more).
565 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: Astell&Kern SR35 and Cayin N3 Ultra. Or put either against your own headphones in the source comparison tool.