The Focal Azurys is 26Ω at 100.0 dB/mW; 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 Azurys needs 7.1 dB more than the Listen Professional to reach the same loudness — 1.0 mW against 0.19 mW.
| Specification | Azurys | Listen Professional |
|---|---|---|
| Impedance | 26 Ω | 32 Ω |
| Sensitivity | 100.0 dB/mW | 107.1 dB/mW |
| Sensitivity (voltage) | 115.9 dB/V | 122.0 dB/V |
| Power for 100 dB | 1.0 mW | 0.19 mW |
| Voltage for 100 dB | 0.16 V | 79 mV |
| Current for 100 dB | 6.2 mA | 2.5 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 3.25 Ω | 4.00 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.
2 sources stay below the audible-hiss threshold with the Azurys 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.
The gap between these two in decibels does not change with volume — it is a property of the two headphones. What changes is the size of the numbers, and it changes fast: every 10 dB costs ten times the power. The row that matters is the one nearest the level you listen at, and for most people that is nearer the top of this table than the bottom.
The Azurys is more demanding than 51% of the 567 non-electrostatic models in this database; the Listen Professional than 25%. Both figures use the same measure as the rest of the site: whichever runs out first against a 2 V, 100 mW dongle, voltage or power.
| dB SPL | Azurys power | Azurys voltage | Listen Professional power | Listen Professional voltage |
|---|---|---|---|---|
| 80 | 0.01 mW | 16 mV | 1.9 µW | 8 mV |
| 85 | 0.03 mW | 29 mV | 6.2 µW | 14 mV |
| 90 | 0.10 mW | 51 mV | 0.02 mW | 25 mV |
| 95 | 0.32 mW | 91 mV | 0.06 mW | 44 mV |
| 100 | 1.0 mW | 0.16 V | 0.19 mW | 79 mV |
| 105 | 3.2 mW | 0.29 V | 0.62 mW | 0.14 V |
105 dB is included because forum power figures are usually quoted there or higher. It is also a level that damages hearing in minutes — how many minutes is its own calculator.
| Source | Price | Headroom, Azurys | Headroom, Listen Professional | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 13.9 dB | 21.9 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 23.2 dB | 30.1 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 20.1 dB | 27.1 dB | 0.6 Ω | 1.0 µV |
Of the 280 sources here, 280 reach 100 dB on both. That is the easy axis. 67 of them also publish an output impedance low enough for both under the one-eighth rule and a noise figure that stays below the audible-hiss threshold with both — the rest either fail one of those or never printed the number at all, and 208 of them are in the second group.
The cheapest of the 67 is the JadeAudio JA11, at $20. It leaves 13.9 dB of headroom on the Azurys and 21.9 dB on the Listen Professional, its output impedance is 0.5 Ω against a one-eighth limit of 3.25 Ω and 4.00 Ω, and its noise figure puts the hiss floor 20 dB and 13 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
Cheapest that satisfies three published numbers is not the same as best, and none of it is about how either headphone sounds. To put either model against a source this page does not mention, or to change the target loudness, use the amplifier matcher.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| Azurys | 15Hz – 22kHz | not printed | not printed |
| Listen Professional | 5 Hz – 23 kHz | ±3 dB | not printed |
Focal prints 15Hz – 22kHz for the Azurys and 5 Hz – 23 kHz for the Listen Professional.
Listen Professional: Focal puts the tolerance in the row heading rather than beside the numbers: the label itself reads "Frequency response (+/- 3dB)".
Only one of the two is a specification. The range printed for the Listen Professional comes with a tolerance; the one printed for the Azurys does not, and a range without a ±dB figure says nothing about how loud that model is at either end of it. The two cannot be compared number against number, however similar they look in the table. Of the 490 models whose maker prints a range, 58 print the tolerance.
None of this is a measurement. What each maker publishes, and what it is worth, is set out in the frequency response audit.
Each model has a page of its own with the full source list, the hiss estimate and the provenance of every figure above: Focal Azurys and Focal Listen Professional. Every figure on this page comes from what Focal published, or is derived from it — what that maker publishes, counted.