Short answer
Both are portable players, $3700 against $2959.
The Shanling M9 Plus reaches 100 dB on 566 of the 567 models here, the Astell&Kern SP3000 on 565.
| Specification | Astell&Kern SP3000 | Shanling M9 Plus |
|---|---|---|
| Power into 32Ω | 340 mW | 520 mW |
| Power into 150Ω | 73 mW | 111 mW |
| Power into 300Ω | 36 mW | 55 mW |
| Power into 600Ω | 18 mW | 28 mW |
| Output impedance | 0.7 Ω | 1 Ω |
| Output noise | 3 µV unverified | not published |
| Price | $3700 | $2959 |
| Headphones it reaches 100 dB on out of 567 | 565 | 566 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Balanced | Astell&Kern SP3000 | Shanling M9 Plus |
|---|---|---|
| Socket | 4.4mm and 2.5mm | 4.4mm |
| Power into 32Ω | 1.2 W derived | 1.1 W |
| Power into 300Ω | 132 mW derived | 120 mW derived |
| Output impedance | 1.6 Ω | 1 Ω |
| Output noise | not published | not published |
| Headphones it reaches 100 dB on out of 567 | 567 | 567 |
Through the balanced sockets the two are level on the same test: each reaches 100 dB on 567 of the 567 models here. Derived figures are worked out from the loads the maker did publish.
| Load | Astell&Kern SP3000 | Shanling M9 Plus |
|---|---|---|
| 32 Ω | Upper bound | Published |
| 150 Ω | Upper bound | Derived |
| 300 Ω | Upper bound | Derived |
| 600 Ω | Upper bound | Derived |
These two columns are not the same kind of number, and that matters more than the gap between them. Shanling M9 Plus publishes a power rating (at 32 Ω); Astell&Kern SP3000 publishes no power figure at any load, only a maximum output voltage, so every milliwatt in its column is a ceiling worked out from that voltage.
A ceiling assumes the amplifier holds that voltage into the load, and nothing on Astell&Kern SP3000’s own sheet says it does. It is the most flattering reading available, and it is used here only because the alternative is a blank. Where the Astell&Kern SP3000 column looks the stronger of the two, treat the difference as unproven rather than measured. 24 of the 280 sources here are in that position, with no published power rating at any load.
1 headphone reaches 100 dB on the Shanling M9 Plus but not on the Astell&Kern SP3000 — Moondrop PARA.
11 headphones are left alone by the Astell&Kern SP3000 under the one-eighth rule but coloured by the Shanling M9 Plus (64 Audio Nio, 64 Audio Volur, Campfire Audio Andromeda 2023, 8 more).
565 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 Audio-Technica ATH-R70X: Shanling M9 Plus has +13 dB of headroom there against +12 dB. 2 dB is about 1.5 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 Shanling M9 Plus because neither maker publishes no output noise figure.
| Headphone | Impedance | Needs | Astell&Kern SP3000 headroom | Shanling M9 Plus headroom | Astell&Kern SP3000 hiss | Shanling M9 Plus hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +34 dB | +36 dB | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +14 dB | +16 dB | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +23 dB | +25 dB | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +18 dB | +20 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +15 dB | +17 dB | not published | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +12 dB | +13 dB | not published | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +7 dB | +9 dB | not published | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | +6 dB | +7 dB | not published | not published |
The Astell&Kern SP3000 costs $741 more than the Shanling M9 Plus. Out of the 567 models here, that difference buys 11 more models left alone under the one-eighth rule.
It does not run one way only: the cheaper Shanling M9 Plus drives one model to 100 dB that the Astell&Kern SP3000 does not, which is the part worth checking against your own headphones before paying the difference.
Only published figures count here; blank axes are counted separately.
Each in full: Astell&Kern SP3000 and Shanling M9 Plus.