The Vision Ears EXT MK II is 10Ω at 108.5 dB/mW; the Vision Ears Phönix Final Edition is 10Ω at 114.6 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 EXT MK II needs 6.1 dB more than the Phönix Final Edition to reach the same loudness — 0.14 mW against 0.03 mW.
| Specification | EXT MK II | Phönix Final Edition |
|---|---|---|
| Impedance | 10 Ω | 10 Ω |
| Sensitivity | 108.5 dB/mW | 114.6 dB/mW |
| Sensitivity (voltage) | 128.5 dB/V | 134.6 dB/V |
| Power for 100 dB | 0.14 mW | 0.03 mW |
| Voltage for 100 dB | 38 mV | 19 mV |
| Current for 100 dB | 3.8 mA | 1.9 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 1.25 Ω | 1.25 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.
25 sources stay below the audible-hiss threshold with the EXT MK II but cross it with the Phönix Final Edition (Kiwi Ears Allegro Mini, FiiO KA13, JDS Labs Atom+ (2nd gen), 22 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: Vision Ears EXT MK II and Vision Ears Phönix Final Edition. Every figure on this page comes from what Vision Ears published, or is derived from it — what that maker publishes, counted.