The Sony MDR-1AM2 is 16Ω at 98.0 dB/mW; the Sony MDR-M1 is 50Ω at 102.0 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 MDR-1AM2 needs 4.0 dB more than the MDR-M1 to reach the same loudness — 1.6 mW against 0.63 mW.
| Specification | MDR-1AM2 | MDR-M1 |
|---|---|---|
| Impedance | 16 Ω | 50 Ω |
| Sensitivity | 98.0 dB/mW | 102.0 dB/mW |
| Sensitivity (voltage) | 116.0 dB/V | 115.0 dB/V |
| Power for 100 dB | 1.6 mW | 0.63 mW |
| Voltage for 100 dB | 0.16 V | 0.18 V |
| Current for 100 dB | 10.0 mA | 3.6 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 2.00 Ω | 6.25 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 MDR-M1 under the one-eighth rule but not for the MDR-1AM2 (Shanling H5).
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: Sony MDR-1AM2 and Sony MDR-M1. Every figure on this page comes from what Sony published, or is derived from it — what that maker publishes, counted.