The Meze 105 AER is 42Ω at 112.0 dB/mW; the Meze 99 Neo is 26Ω at 103.0 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 99 Neo needs 9.0 dB more than the 105 AER to reach the same loudness — 0.50 mW against 0.06 mW.
| Specification | 105 AER | 99 Neo |
|---|---|---|
| Impedance | 42 Ω | 26 Ω |
| Sensitivity | 112.0 dB/mW | 103.0 dB/mW |
| Sensitivity (voltage) | 125.8 dB/V | 118.9 dB/V |
| Power for 100 dB | 0.06 mW | 0.50 mW |
| Voltage for 100 dB | 51 mV | 0.11 V |
| Current for 100 dB | 1.2 mA | 4.4 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 5.25 Ω | 3.25 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.
1 source is low enough in output impedance for the 105 AER under the one-eighth rule but not for the 99 Neo (Shanling H5).
13 sources stay below the audible-hiss threshold with the 99 Neo but cross it with the 105 AER (FiiO BTR11, FiiO K11 R2R, Lake People G103-S Mk II, 10 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: Meze 105 AER and Meze 99 Neo. Every figure on this page comes from what Meze published, or is derived from it — what that maker publishes, counted.