The Astell&Kern HC3 is a USB dongle at $179. It delivers 125 mW into 32Ω and 13 mW into 300Ω, which ranks it 72 of 88 for raw power among the sources in this database.
Measured at 100 dB SPL it has comfortable headroom on 264 of the 310 dynamic and planar headphones catalogued here, enough but not generous on 44 and only marginal on 2. Single-ended only, tuned rather than measured — Astell&Kern publishes voltage and impedance but no power rating at any load.
The manufacturer publishes a maximum output of 2.0 V but no power rating at any load. Every figure above is therefore a ceiling: the real output into a low impedance will be lower, possibly much lower.
Derivation holds output voltage steady between and beyond the published loads rather than output power, because that is what an amplifier actually does. The full method is written up here.
Source: astellnkern.co.uk.
| Load | Power | Status | How it was arrived at |
|---|---|---|---|
| 32 Ω | 125 mW | Upper bound | the manufacturer publishes a maximum output voltage but no power rating, so this is a ceiling, not a rating |
| 150 Ω | 27 mW | Upper bound | the manufacturer publishes a maximum output voltage but no power rating, so this is a ceiling, not a rating |
| 300 Ω | 13 mW | Upper bound | the manufacturer publishes a maximum output voltage but no power rating, so this is a ceiling, not a rating |
| 600 Ω | 6.7 mW | Upper bound | the manufacturer publishes a maximum output voltage but no power rating, so this is a ceiling, not a rating |
Ordered from easiest to hardest to drive. Headroom is measured at 100 dB SPL, which is louder than almost anyone listens — a small negative number means the source still plays loud, just without reserve for peaks.
These figures come from each manufacturer's own sensitivity rating. A handful of planars — the HiFiMAN Susvara and HE-6se and the Abyss AB-1266 in particular — are widely reported to need far more than their published sensitivity implies, so treat a bare pass on those as optimistic rather than settled.
| Headphone | Impedance | dB/mW | Needs | Headroom | Verdict |
|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 114.0 | 0.04 mW | +29 dB | Comfortable damping |
| 64 Audio U12t | 13 Ω | 108.0 | 0.16 mW | +25 dB | Comfortable damping |
| Shure SE215 | 17 Ω | 107.0 | 0.20 mW | +25 dB | Comfortable |
| Moondrop Aria | 32 Ω | 107.0 | 0.20 mW | +28 dB | Comfortable |
| Sennheiser IE 200 | 18 Ω | 104.0 | 0.40 mW | +22 dB | Comfortable |
| Audeze LCD-X 2021 | 20 Ω | 103.0 | 0.50 mW | +22 dB | Comfortable |
| Sennheiser HD 25 (1-II) | 70 Ω | 108.0 | 0.16 mW | +26 dB | Comfortable |
| Sony MDR-7506 | 63 Ω | 106.0 | 0.25 mW | +24 dB | Comfortable |
| Meze 99 Classics | 32 Ω | 103.0 | 0.50 mW | +24 dB | Comfortable |
| Focal Clear MG | 55 Ω | 104.0 | 0.40 mW | +23 dB | Comfortable |
| Philips SHP9500 | 32 Ω | 101.0 | 0.79 mW | +22 dB | Comfortable |
| Truthear Hexa | 21 Ω | 99.0 | 1.3 mW | +18 dB | Comfortable |
| Focal Utopia | 80 Ω | 104.0 | 0.40 mW | +21 dB | Comfortable |
| Meze Empyrean | 32 Ω | 100.0 | 1.0 mW | +21 dB | Comfortable |
| Campfire Audio Andromeda 2020 | 9 Ω | 94.0 | 4.0 mW | +9 dB | Enough damping |
| Etymotic ER2SE | 15 Ω | 96.0 | 2.5 mW | +14 dB | Comfortable damping |
| AKG K371 | 32 Ω | 99.0 | 1.3 mW | +20 dB | Comfortable |
| Grado SR80x | 32 Ω | 99.0 | 1.3 mW | +20 dB | Comfortable |
| Audio-Technica ATH-M50X | 38 Ω | 99.0 | 1.3 mW | +19 dB | Comfortable |
| Beyerdynamic DT 900 Pro X | 48 Ω | 100.0 | 1.0 mW | +19 dB | Comfortable |
| Audeze LCD-2 Classic | 70 Ω | 101.0 | 0.79 mW | +19 dB | Comfortable |
| Dan Clark Audio AEON 2 Closed | 13 Ω | 92.0 | 6.3 mW | +9 dB | Enough damping |
| Sennheiser HD 560S | 120 Ω | 101.0 | 0.79 mW | +16 dB | Comfortable |
| HiFiMAN Edition XS | 18 Ω | 92.0 | 6.3 mW | +10 dB | Comfortable |
| HiFiMAN Arya Stealth | 32 Ω | 94.0 | 4.0 mW | +15 dB | Comfortable |
| Audeze LCD-5 | 14 Ω | 90.0 | 10 mW | +7 dB | Enough damping |
| HiFiMAN Sundara | 37 Ω | 94.0 | 4.0 mW | +14 dB | Comfortable |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 102.0 | 0.63 mW | +14 dB | Comfortable |
| HiFiMAN HE400se | 32 Ω | 91.0 | 7.9 mW | +12 dB | Comfortable |
| AKG K702 | 62 Ω | 93.0 | 5.0 mW | +11 dB | Comfortable |
| Fostex T50RP MK3 | 50 Ω | 92.0 | 6.3 mW | +11 dB | Comfortable |
| ZMF Verite Closed | 300 Ω | 99.0 | 1.3 mW | +10 dB | Comfortable |
| Dan Clark Audio Stealth | 23 Ω | 87.0 | 20 mW | +7 dB | Enough |
| Sennheiser HD 650 | 300 Ω | 98.0 | 1.6 mW | +9 dB | Enough |
| ZMF Atrium | 300 Ω | 98.0 | 1.6 mW | +9 dB | Enough |
| Audio-Technica ATH-R70X | 470 Ω | 99.0 | 1.3 mW | +8 dB | Enough |
| Sennheiser HD 600 | 300 Ω | 97.0 | 2.0 mW | +8 dB | Enough |
| Sennheiser HD 800S | 300 Ω | 97.0 | 2.0 mW | +8 dB | Enough |
| Beyerdynamic DT 770 Pro (250Ω) | 250 Ω | 96.0 | 2.5 mW | +8 dB | Enough |
| Abyss AB-1266 Phi TC | 42 Ω | 88.0 | 16 mW | +8 dB | Enough |
| HiFiMAN Susvara | 60 Ω | 83.0 | 50 mW | +1 dB | Marginal |
The manufacturer does not publish an output noise figure for this source, so the hiss estimate that runs on every other page here cannot be run on this one. Rather than substitute a plausible number, this page leaves the question open.
If you know the noise figure from a measurement you trust, the hiss calculator takes it directly and tells you where that noise lands in your own in-ears.
At 2.0 Ω output impedance, the one-eighth rule says this source suits headphones of 16.0Ω and above. 35 of the 310 models here fall below that, mostly multi-driver in-ears, where the mismatch tilts the frequency response audibly rather than subtly.
The rule is a rule of thumb, not physics: a source impedance below one eighth of the headphone's keeps the interaction under about 1 dB. The checker works it out for any pair.
$190 · 280 mW into 32Ω · not published out
Compare →$149 · 140 mW into 32Ω · 1.0 Ω out
Compare →$139 · 138 mW into 32Ω · not published out
Compare →$219 · 125 mW into 32Ω · 0.9 Ω out
Compare →$119 · 125 mW into 32Ω · 0.2 Ω out
Compare →$110 · 190 mW into 32Ω · 0.4 Ω out
Compare →Or put any two side by side in the source comparison tool, or run your own headphones through the amplifier matcher.