The Beyerdynamic DT 1990 Pro (250Ω) is 250Ω at 102.0 dB/mW; the Dan Clark Audio Stealth is 23Ω at 90.0 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 Dan Clark Audio Stealth needs 12.0 dB more than the Beyerdynamic DT 1990 Pro (250Ω) to reach the same loudness — 10 mW against 0.63 mW.
| Specification | Beyerdynamic DT 1990 Pro (250Ω) | Dan Clark Audio Stealth |
|---|---|---|
| Impedance | 250 Ω | 23 Ω |
| Sensitivity | 102.0 dB/mW | 90.0 dB/mW |
| Sensitivity (voltage) | 108.0 dB/V | 106.4 dB/V |
| Power for 100 dB | 0.63 mW | 10 mW |
| Voltage for 100 dB | 0.40 V | 0.48 V |
| Current for 100 dB | 1.6 mA | 20.9 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 31.25 Ω | 2.88 Ω |
| Sources that reach 100 dB out of 280 | 280 | 279 |
1 of the 280 sources has the power for the Beyerdynamic DT 1990 Pro (250Ω) but not for the Dan Clark Audio Stealth — Steinberg UR22C.
19 sources are low enough in output impedance for the Beyerdynamic DT 1990 Pro (250Ω) under the one-eighth rule but not for the Dan Clark Audio Stealth (Zoom AMS-22, Arturia MiniFuse 2, Arturia MiniFuse 1, 16 more).
279 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: Beyerdynamic DT 1990 Pro (250Ω) and Dan Clark Audio Stealth. Every figure on this page comes from what Beyerdynamic and Dan Clark Audio published, or is derived from it — what Beyerdynamic publishes and what Dan Clark Audio publishes, both counted.