The Moondrop Variations is 15.2Ω at 99.8 dB/mW; the Truthear Hexa is 20.5Ω at 103.1 dB/mW. This page is only about what they ask of an amplifier — not how they sound, which no specification on either sheet can tell you.
The Moondrop Variations needs 3.3 dB more than the Truthear Hexa to reach the same loudness — 1.0 mW against 0.49 mW.
| Specification | Moondrop Variations | Truthear Hexa |
|---|---|---|
| Impedance | 15.2 Ω | 20.5 Ω |
| Sensitivity | 99.8 dB/mW | 103.1 dB/mW |
| Sensitivity (voltage) | 118.0 dB/V | 120.0 dB/V |
| Power for 100 dB | 1.0 mW | 0.49 mW |
| Voltage for 100 dB | 0.13 V | 0.10 V |
| Current for 100 dB | 8.3 mA | 4.9 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 1.90 Ω | 2.56 Ω |
| Sources that reach 100 dB out of 280 | 280 | 280 |
Every source in the database that drives one of them drives the other. On power, the choice between these two changes nothing about what amplifier you need.
3 sources are low enough in output impedance for the Truthear Hexa under the one-eighth rule but not for the Moondrop Variations (Astell&Kern HC3, RME Fireface UFX II, RME Fireface UFX III).
280 of the 280 sources here reach 100 dB on both. That count is about power only — the output-impedance and hiss lines above are separate questions, and a source can pass this one and fail those.
Each model has a page of its own with the full source list, the hiss estimate and the provenance of every figure above: Moondrop Variations and Truthear Hexa. Every figure on this page comes from what Moondrop and Truthear published, or is derived from it — what Moondrop publishes and what Truthear publishes, both counted.