Short answer
Both are dongles, $160 against $250.
The Questyle M15 reaches 100 dB on 565 of the 567 models here, the ddHiFi TC44Grip on 557.
| Specification | ddHiFi TC44Grip | Questyle M15 |
|---|---|---|
| Power into 32Ω | 80 mW | 300 mW |
| Power into 150Ω | 17 mW | 110 mW |
| Power into 300Ω | 8.5 mW | 55 mW |
| Power into 600Ω | 4.3 mW | 28 mW |
| Output impedance | not published | 0.5 Ω unverified |
| Output noise | not published | 3 µV unverified |
| Price | $160 | $250 |
| Headphones it reaches 100 dB on out of 567 | 557 | 565 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Balanced | ddHiFi TC44Grip | Questyle M15 |
|---|---|---|
| Socket | 4.4mm | no separate rating |
| 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 Questyle M15 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 | ddHiFi TC44Grip | Questyle M15 |
|---|---|---|
| 32 Ω | Published | Unverified |
| 150 Ω | Derived | Unverified |
| 300 Ω | Derived | Unverified |
| 600 Ω | Derived | Unverified |
Questyle M15 publishes no electrical specification at all. That is true of 10 of the 280 sources here, and the figures in that column come from independent measurement rather than from a maker document — which is not worse, but it is not the same thing, and it cannot be checked against anything the maker will stand behind.
The ddHiFi TC44Grip column does stand on a power rating its maker printed, at one of these four loads at least. Reading the two straight across sets one kind of claim against another, and nobody has written down the conditions of both side by side.
8 headphones reach 100 dB on the Questyle M15 but not on the ddHiFi TC44Grip — HiFiMAN Susvara, Moondrop COSMO, Moondrop PARA 2, 5 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 Audio-Technica ATH-R70X: Questyle M15 has +13 dB of headroom there against +5 dB. 8 dB is about 6.5 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for ddHiFi TC44Grip and Questyle M15 because neither maker publishes no output noise figure.
| Headphone | Impedance | Needs | ddHiFi TC44Grip headroom | Questyle M15 headroom | ddHiFi TC44Grip hiss | Questyle M15 hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +28 dB | +33 dB | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +8 dB | +13 dB | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +17 dB | +23 dB | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +12 dB | +20 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +9 dB | +15 dB | not published | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +5 dB | +13 dB | not published | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +1 dB | +9 dB | not published | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | -1 dB | +6 dB | not published | not published |
The Questyle M15 costs $90 more than the ddHiFi TC44Grip. Out of the 567 models here, that difference buys 8 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 has a page of its own with a full headphone list and the provenance of every figure — worth opening here, because Questyle M15 has published no electrical specification at all and everything above comes from independent measurement: ddHiFi TC44Grip and Questyle M15.