The Focal Elex (Drop) is 80Ω at 104.0 dB (no figure from the maker at all); the Focal Listen Professional is 32Ω at 107.1 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 Elex (Drop) needs 3.1 dB more than the Listen Professional to reach the same loudness — 0.40 mW against 0.19 mW.
| Specification | Elex (Drop) | Listen Professional |
|---|---|---|
| Impedance | 80 Ω | 32 Ω |
| Sensitivity | 104.0 dB | 107.1 dB/mW |
| Sensitivity (voltage) | 115.0 dB/V | 122.0 dB/V |
| Power for 100 dB | 0.40 mW | 0.19 mW |
| Voltage for 100 dB | 0.18 V | 79 mV |
| Current for 100 dB | 2.2 mA | 2.5 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 10.00 Ω | 4.00 Ω |
| Sources that reach 100 dB out of 280 | 280 | 280 |
One caution before reading the rows. For Focal Elex (Drop) the maker publishes no sensitivity figure at all. The number in the table was collected when this database was first built and has never been traced to a manufacturer document, so treat every row below it as an estimate rather than a specification.
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.
10 sources are low enough in output impedance for the Elex (Drop) under the one-eighth rule but not for the Listen Professional (Zoom AMS-22, Arturia MiniFuse 2, Arturia MiniFuse 1, 7 more).
2 sources stay below the audible-hiss threshold with the Elex (Drop) but cross it with the Listen Professional (FiiO BTR11, Rupert Neve RNHP).
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: Focal Elex (Drop) and Focal Listen Professional. Each figure on this page is labelled on those pages with where it came from, including the ones Focal never published — what that maker publishes, counted.