Both are portable players, $3700 against $800. 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 SP3000 | Astell&Kern SR35 |
|---|---|---|
| Power into 32Ω | 340 mW | 300 mW |
| Power into 150Ω | 73 mW | 64 mW |
| Power into 300Ω | 36 mW | 32 mW |
| Power into 600Ω | 18 mW | 16 mW |
| Output impedance | 0.7 Ω | 1.1 Ω |
| Output noise | 3 µV unverified | 4 µV unverified |
| Price | $3700 | $800 |
| 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.
| Load | Astell&Kern SP3000 | Astell&Kern SR35 |
|---|---|---|
| 32 Ω | Upper bound | Upper bound |
| 150 Ω | Upper bound | Upper bound |
| 300 Ω | Upper bound | Upper bound |
| 600 Ω | Upper bound | Upper bound |
Neither maker publishes a power rating at any load. Both columns above are ceilings, worked out from a maximum output voltage on the assumption that the amplifier holds it into the load — the most flattering reading available for either. 24 of the 280 sources here are in that position. Whichever of the two looks the stronger on power, the difference is unproven; the output-impedance and noise rows are the ones to go on.
What each of these labels means, and why a derived figure is still worth printing, is set out in how this data was built.
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.
24 headphones are left alone by the Astell&Kern SP3000 under the one-eighth rule but coloured by the Astell&Kern SR35 (64 Audio Nio, 64 Audio U18s, 64 Audio Volur, 21 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.
The counts above say how many models the two treat differently. This says by how much. The same 8 headphones appear on every page of this kind, ordered from the easiest to drive to the hardest, so a row can be read across pages as well as across columns. Headroom is at a 100 dB SPL peak.
The widest gap on the list is the Sennheiser HD 600: Astell&Kern SP3000 has +7 dB of headroom there against +7 dB. 1 dB is about 1.1 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for Astell&Kern SP3000 and Astell&Kern SR35 because neither maker publishes no output noise figure. That is a gap in the specification, not a quiet amplifier, and it is left blank here rather than filled with a plausible number.
| Headphone | Impedance | Needs | Astell&Kern SP3000 headroom | Astell&Kern SR35 headroom | Astell&Kern SP3000 hiss | Astell&Kern SR35 hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +34 dB | +33 dB | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +14 dB | +13 dB | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +23 dB | +22 dB | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +18 dB | +18 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +15 dB | +15 dB | not published | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +12 dB | +11 dB | not published | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +7 dB | +7 dB | not published | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | +6 dB | +5 dB | not published | not published |
The Astell&Kern SP3000 costs $2900 more than the Astell&Kern SR35. Out of the 567 models here, that difference buys 24 more models left alone under the one-eighth rule.
Nothing runs the other way: there is no axis here on which the cheaper of the two does better.
Everything in this paragraph counts only figures the two makers published. An advantage on an axis one of them leaves blank cannot be counted, and is not counted — how often that happens is its own page.
Each has a page of its own with every power figure traced to what the maker published and a full headphone list: Astell&Kern SP3000 and Astell&Kern SR35. Or put either against your own headphones in the source comparison tool.