Short answer
Both are dongles, $179 against $119.
On raw power they are level: each reaches 100 dB on 561 of the 567 non-electrostatic models here.
| Specification | Astell&Kern HC3 | iBasso DC04 Pro |
|---|---|---|
| Power into 32Ω | 125 mW | 125 mW |
| Power into 150Ω | 27 mW | 27 mW |
| Power into 300Ω | 13 mW | 13 mW |
| Power into 600Ω | 6.7 mW | 6.7 mW |
| Output impedance | 2.0 Ω | 0.2 Ω |
| Output noise | not published | 2.5 µV unverified |
| Price | $179 | $119 |
| Headphones it reaches 100 dB on out of 567 | 561 | 561 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Balanced | Astell&Kern HC3 | iBasso DC04 Pro |
|---|---|---|
| Socket | no separate rating | 4.4mm |
| Power into 32Ω | — | 281 mW derived |
| Power into 300Ω | — | 30 mW derived |
| Output impedance | — | 0.4 Ω |
| Output noise | — | not published |
| Headphones it reaches 100 dB on out of 567 | — | 565 |
Only the iBasso DC04 Pro has a separate balanced rating from its maker; through it, it reaches 100 dB on 565 of the 567 models here. The Astell&Kern HC3 may still have a balanced socket — its spec sheet simply gives no figure for one, so there is nothing to put beside it. Derived figures are worked out from the loads the maker did publish.
| Load | Astell&Kern HC3 | iBasso DC04 Pro |
|---|---|---|
| 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.
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.
89 headphones are left alone by the iBasso DC04 Pro under the one-eighth rule but coloured by the Astell&Kern HC3 (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Nio, 86 more).
561 of the 567 models here reach 100 dB on both.
Headroom is at a 100 dB SPL peak.
Across all eight the two stay within half a decibel of each other, which is a way of saying that on power this pair is one product.
The hiss columns are empty for Astell&Kern HC3 and iBasso DC04 Pro because neither maker publishes no output noise figure.
| Headphone | Impedance | Needs | Astell&Kern HC3 headroom | iBasso DC04 Pro headroom | Astell&Kern HC3 hiss | iBasso DC04 Pro hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +29 dB damping | +29 dB | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +9 dB damping | +9 dB | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +19 dB | +19 dB | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +14 dB | +14 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +11 dB | +11 dB | not published | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +7 dB | +7 dB | not published | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +3 dB | +3 dB | not published | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | +1 dB | +1 dB | not published | not published |
The Astell&Kern HC3 costs $60 more than the iBasso DC04 Pro, and on these three axes the money buys nothing: among the 567 models here there is not one that the Astell&Kern HC3 handles and the iBasso DC04 Pro does not — not on power, not on the one-eighth rule, not on hiss. The traffic runs the other way: the cheaper iBasso DC04 Pro leaves 89 models alone under the one-eighth rule that the Astell&Kern HC3 does not.
Only published figures count here; blank axes are counted separately.
Each in full: Astell&Kern HC3 and iBasso DC04 Pro.