Short answer
Both are dongles, $179 against $160.
The Astell&Kern HC3 reaches 100 dB on 561 of the 567 models here, the ddHiFi TC44Grip on 557.
| Specification | Astell&Kern HC3 | ddHiFi TC44Grip |
|---|---|---|
| Power into 32Ω | 125 mW | 80 mW |
| Power into 150Ω | 27 mW | 17 mW |
| Power into 300Ω | 13 mW | 8.5 mW |
| Power into 600Ω | 6.7 mW | 4.3 mW |
| Output impedance | 2.0 Ω | not published |
| Output noise | not published | not published |
| Price | $179 | $160 |
| Headphones it reaches 100 dB on out of 567 | 561 | 557 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Balanced | Astell&Kern HC3 | ddHiFi TC44Grip |
|---|---|---|
| Socket | no separate rating | 4.4mm |
| Power into 32Ω | — | 330 mW |
| Power into 300Ω | — | 35 mW derived |
| Output impedance | — | not published |
| Output noise | — | not published |
| Headphones it reaches 100 dB on out of 567 | — | 565 |
Only the ddHiFi TC44Grip 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 | ddHiFi TC44Grip |
|---|---|---|
| 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. ddHiFi TC44Grip publishes a power rating (at 32 Ω); Astell&Kern HC3 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 HC3’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 HC3 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.
4 headphones reach 100 dB on the Astell&Kern HC3 but not on the ddHiFi TC44Grip — HiFiMAN Susvara, Moondrop PARA 2, Moondrop VENUS, 1 more.
557 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 Sennheiser HD 600: Astell&Kern HC3 has +3 dB of headroom there against +1 dB. 2 dB is about 1.6 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for Astell&Kern HC3 and ddHiFi TC44Grip because neither maker publishes no output noise figure.
| Headphone | Impedance | Needs | Astell&Kern HC3 headroom | ddHiFi TC44Grip headroom | Astell&Kern HC3 hiss | ddHiFi TC44Grip hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +29 dB damping | +28 dB | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +9 dB damping | +8 dB | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +19 dB | +17 dB | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +14 dB | +12 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +11 dB | +9 dB | not published | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +7 dB | +5 dB | not published | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +3 dB | +1 dB | not published | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | +1 dB | -1 dB | not published | not published |
The Astell&Kern HC3 costs $19 more than the ddHiFi TC44Grip. Out of the 567 models here, that difference buys 4 more models driven to 100 dB.
Nothing runs the other way: there is no axis here on which the cheaper of the two does better.
Only published figures count here; blank axes are counted separately.
Each in full: Astell&Kern HC3 and ddHiFi TC44Grip.