The Beyerdynamic DT 240 Pro is 34Ω at 99.0 dB/mW; the Beyerdynamic DT 270 PRO is 45Ω at 96.0 dB (no reference unit printed). 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 DT 270 PRO needs 3.0 dB more than the DT 240 Pro to reach the same loudness — 2.5 mW against 1.3 mW.
| Specification | DT 240 Pro | DT 270 PRO |
|---|---|---|
| Impedance | 34 Ω | 45 Ω |
| Sensitivity | 99.0 dB/mW | 96.0 dB |
| Sensitivity (voltage) | 113.7 dB/V | 109.5 dB/V |
| Power for 100 dB | 1.3 mW | 2.5 mW |
| Voltage for 100 dB | 0.21 V | 0.34 V |
| Current for 100 dB | 6.1 mA | 7.5 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 4.25 Ω | 5.62 Ω |
| Sources that reach 100 dB out of 280 | 280 | 280 |
One caution before reading the rows. Beyerdynamic DT 270 PRO printed a decibel figure with no reference unit, so this page reads it as per milliwatt. If it is really per volt, that model needs far more than the table says. Why the two readings differ by so much.
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.
1 source is low enough in output impedance for the DT 270 PRO under the one-eighth rule but not for the DT 240 Pro (Shanling H5).
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: Beyerdynamic DT 240 Pro and Beyerdynamic DT 270 PRO. Each figure on this page is labelled on those pages with where it came from, including the ones Beyerdynamic never published — what that maker publishes, counted.