The Westone MACH 10 is 80Ω at 103.0 dB (no reference unit printed); the Westone MACH 20 is 96Ω at 110.0 dB (no reference unit printed). 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 MACH 10 needs 7.0 dB more than the MACH 20 to reach the same loudness — 0.50 mW against 0.10 mW.
| Specification | MACH 10 | MACH 20 |
|---|---|---|
| Impedance | 80 Ω | 96 Ω |
| Sensitivity | 103.0 dB | 110.0 dB |
| Sensitivity (voltage) | 114.0 dB/V | 120.2 dB/V |
| Power for 100 dB | 0.50 mW | 0.10 mW |
| Voltage for 100 dB | 0.20 V | 98 mV |
| Current for 100 dB | 2.5 mA | 1.0 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 10.00 Ω | 12.00 Ω |
| Sources that reach 100 dB out of 280 | 280 | 280 |
One caution before reading the rows. Westone MACH 10 and Westone MACH 20 printed a decibel figure with no reference unit, so this page reads it as per milliwatt. If it is really per volt, each of them needs far more than the table says. Why the two readings differ by so much.
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.
7 sources are low enough in output impedance for the MACH 20 under the one-eighth rule but not for the MACH 10 (Focusrite Scarlett 4i4 4th gen, Zoom UAC-232, Focusrite Scarlett 16i16 (4th Gen), 4 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: Westone MACH 10 and Westone MACH 20. Each figure on this page is labelled on those pages with where it came from, including the ones Westone never published — what that maker publishes, counted.