Every model here is 150 Ω or above, and what they have in common is not that they need a lot of power — most of them need very little. They need voltage, and a source that runs out of voltage swing before it runs out of current will sound quiet on these while driving a 16 Ω in-ear to painful levels.
That is why both columns are here. Read the volts column against the output voltage your source publishes, not the milliwatt column against its power rating — the milliwatts are what the volts happen to work out to at this impedance, and they are the figure that misleads on high-impedance headphones.
One thing to read this list with. Every position on it is calculated from sensitivity, and 9 of these 38 models have a sensitivity figure whose reference unit the maker never printed. The number is read as per milliwatt here, because that is the commoner convention on a spec sheet that omits the unit — but if one of them meant per volt, that model is less sensitive than this list assumes, and by how much depends on its impedance: from 2.2 dB at 600Ω to 8.2 dB at 150Ω across the ones affected here. Each model page says which case it is in and shows both readings. A list that does not mention this is not more accurate than this one; it is only quieter about the same problem.
| Headphone | Impedance | Sensitivity | Volts for 100 dB | Power for 100 dB |
|---|---|---|---|---|
| Beyerdynamic DT 880 Edition (600Ω) | 600 Ω | 96.0 dB/mW | 1.23 V | 2.5 mW |
| Beyerdynamic DT 990 Edition (600Ω) | 600 Ω | 96.0 dB/mW | 1.23 V | 2.5 mW |
| Beyerdynamic T1 2nd Gen (600Ω) | 600 Ω | 102.0 dB/mW | 0.62 V | 0.63 mW |
| Audio-Technica ATH-R70X | 470 Ω | 98.0 dB/mW | 0.86 V | 1.6 mW |
| Audio-Technica ATH-R70xa | 470 Ω | 97.0 dB/mW | 0.97 V | 2.0 mW |
| Audio-Technica ATH-ADX5000 | 420 Ω | 100.0 dB/mW | 0.65 V | 1.0 mW |
| FiiO FT3 (350Ω) | 350 Ω | 100.4 dB/mW | 0.56 V | 0.91 mW |
| Sennheiser HD 600 | 300 Ω | 91.8 dB/mW | 1.41 V | 6.6 mW |
| Sennheiser HD 650 | 300 Ω | 97.8 dB/mW | 0.71 V | 1.7 mW |
| Sennheiser HD 660S2 | 300 Ω | 98.8 dB/mW | 0.63 V | 1.3 mW |
| Sennheiser HD 6XX (Drop) | 300 Ω | 97.8 dB/mW | 0.71 V | 1.7 mW |
| Sennheiser HD 800 | 300 Ω | 96.8 dB/mW | 0.79 V | 2.1 mW |
| Sennheiser HD 800S | 300 Ω | 96.8 dB/mW | 0.79 V | 2.1 mW |
| Sennheiser HD 820 | 300 Ω | 97.8 dB/mW | 0.71 V | 1.7 mW |
| ZMF Aeolus | 300 Ω | 97.0 dB/mW | 0.77 V | 2.0 mW |
The table shows the first 15 of 38. The rest are in the full headphone database, where every figure is labelled with where it came from.
529 of the 567 non-electrostatic models in this database are not on this list because it covers one part of the catalogue rather than all of it. Nothing was excluded for failing a test and nothing is missing a figure; this one is a category, not a ranking threshold.
This is not a ranking of sound quality and cannot be. It sorts one number that manufacturers printed, and manufacturers do not print anything about how their products sound. Every row links to that product’s own page, where each figure is labelled with the document it came from.
Quietest sources for sensitive in-ears · Lowest published output impedance · Most power into 300 Ω · Sources that drive everything here · Audio interfaces as headphone amplifiers · Sources under $100 · Hardest headphones to drive · Most sensitive in-ears · Quietest desktop sources · What balanced actually gains · Portable players by power · Most power per dollar