The Audeze LCD-4 is 200Ω at 97.0 dB/mW; the Audeze LCD-5s is 35Ω 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 LCD-5s needs 7.0 dB more than the LCD-4 to reach the same loudness — 10 mW against 2.0 mW.
| Specification | LCD-4 | LCD-5s |
|---|---|---|
| Impedance | 200 Ω | 35 Ω |
| Sensitivity | 97.0 dB/mW | 90.0 dB/mW |
| Sensitivity (voltage) | 104.0 dB/V | 104.6 dB/V |
| Power for 100 dB | 2.0 mW | 10 mW |
| Voltage for 100 dB | 0.63 V | 0.59 V |
| Current for 100 dB | 3.2 mA | 16.9 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 25.00 Ω | 4.38 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.
19 sources are low enough in output impedance for the LCD-4 under the one-eighth rule but not for the LCD-5s (Zoom AMS-22, Arturia MiniFuse 2, Arturia MiniFuse 1, 16 more).
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: Audeze LCD-4 and Audeze LCD-5s. Every figure on this page comes from what Audeze published, or is derived from it — what that maker publishes, counted.