Short answer
Both are dongles, $160 against $139.
The Hidizs S9 Pro Plus reaches 100 dB on 562 of the 567 models here, the ddHiFi TC44Grip on 557.
| Specification | ddHiFi TC44Grip | Hidizs S9 Pro Plus |
|---|---|---|
| Power into 32Ω | 80 mW | 138 mW |
| Power into 150Ω | 17 mW | 29 mW |
| Power into 300Ω | 8.5 mW | 15 mW |
| Power into 600Ω | 4.3 mW | 7.4 mW |
| Output impedance | not published | not published |
| Output noise | not published | not published |
| Price | $160 | $139 |
| Headphones it reaches 100 dB on out of 567 | 557 | 562 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Balanced | ddHiFi TC44Grip | Hidizs S9 Pro Plus |
|---|---|---|
| Socket | 4.4mm | 4.4mm |
| Power into 32Ω | 330 mW | 180 mW |
| Power into 300Ω | 35 mW derived | 19 mW derived |
| Output impedance | not published | not published |
| Output noise | not published | not published |
| Headphones it reaches 100 dB on out of 567 | 565 | 564 |
Through the balanced sockets the ddHiFi TC44Grip reaches 100 dB on 565 of the 567 models here and the Hidizs S9 Pro Plus on 564. Derived figures are worked out from the loads the maker did publish.
| Load | ddHiFi TC44Grip | Hidizs S9 Pro Plus |
|---|---|---|
| 32 Ω | Published | Published |
| 150 Ω | Derived | Derived |
| 300 Ω | Derived | Derived |
| 600 Ω | Derived | Derived |
Both makers publish a power rating. ddHiFi TC44Grip publishes at 32 Ω; Hidizs S9 Pro Plus at 32 Ω. The other rows are worked out from those.
The two publish at the same loads, which is the one case where the rows of this table can be read straight across.
5 headphones reach 100 dB on the Hidizs S9 Pro Plus but not on the ddHiFi TC44Grip — HiFiMAN Susvara, Moondrop PARA 2, Moondrop VENUS, 2 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: Hidizs S9 Pro Plus has +3 dB of headroom there against +1 dB. 2 dB is about 1.7 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for ddHiFi TC44Grip and Hidizs S9 Pro Plus because neither maker publishes no output noise figure.
| Headphone | Impedance | Needs | ddHiFi TC44Grip headroom | Hidizs S9 Pro Plus headroom | ddHiFi TC44Grip hiss | Hidizs S9 Pro Plus hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +28 dB | +30 dB | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +8 dB | +10 dB | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +17 dB | +19 dB | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +12 dB | +14 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +9 dB | +11 dB | not published | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +5 dB | +8 dB | not published | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +1 dB | +3 dB | not published | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | -1 dB | +2 dB | not published | not published |
The ddHiFi TC44Grip costs $21 more than the Hidizs S9 Pro Plus, and on these three axes the money buys nothing: among the 567 models here there is not one that the ddHiFi TC44Grip handles and the Hidizs S9 Pro Plus does not — not on power, not on the one-eighth rule, not on hiss. The traffic runs the other way: the cheaper Hidizs S9 Pro Plus drives 5 models to 100 dB that the ddHiFi TC44Grip does not.
Only published figures count here; blank axes are counted separately.
Each in full: ddHiFi TC44Grip and Hidizs S9 Pro Plus.