The Westone MACH 20 is 96Ω at 110.0 dB (no reference unit printed); the Westone Pro X10 is 19Ω at 114.0 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 MACH 20 needs 4.0 dB more than the Pro X10 to reach the same loudness — 0.10 mW against 0.04 mW.
| Specification | MACH 20 | Pro X10 |
|---|---|---|
| Impedance | 96 Ω | 19 Ω |
| Sensitivity | 110.0 dB | 114.0 dB/mW |
| Sensitivity (voltage) | 120.2 dB/V | 131.2 dB/V |
| Power for 100 dB | 0.10 mW | 0.04 mW |
| Voltage for 100 dB | 98 mV | 28 mV |
| Current for 100 dB | 1.0 mA | 1.4 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 12.00 Ω | 2.38 Ω |
| Sources that reach 100 dB out of 280 | 280 | 280 |
One caution before reading the rows. 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, that model 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.
17 sources are low enough in output impedance for the MACH 20 under the one-eighth rule but not for the Pro X10 (Zoom AMS-22, Arturia MiniFuse 2, Arturia MiniFuse 1, 14 more).
31 sources stay below the audible-hiss threshold with the MACH 20 but cross it with the Pro X10 (Kiwi Ears Allegro Mini, FiiO BTR11, Fosi Audio SK02, 28 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.
The gap between these two in decibels does not change with volume — it is a property of the two headphones. What changes is the size of the numbers, and it changes fast: every 10 dB costs ten times the power. The row that matters is the one nearest the level you listen at, and for most people that is nearer the top of this table than the bottom.
The MACH 20 is more demanding than 31% of the 567 non-electrostatic models in this database; the Pro X10 than 2%. Both figures use the same measure as the rest of the site: whichever runs out first against a 2 V, 100 mW dongle, voltage or power.
| dB SPL | MACH 20 power | MACH 20 voltage | Pro X10 power | Pro X10 voltage |
|---|---|---|---|---|
| 80 | 1.0 µW | 10 mV | 0.4 µW | 3 mV |
| 85 | 3.2 µW | 17 mV | 1.3 µW | 5 mV |
| 90 | 0.01 mW | 31 mV | 4.0 µW | 9 mV |
| 95 | 0.03 mW | 55 mV | 0.01 mW | 15 mV |
| 100 | 0.10 mW | 98 mV | 0.04 mW | 28 mV |
| 105 | 0.32 mW | 0.17 V | 0.13 mW | 49 mV |
105 dB is included because forum power figures are usually quoted there or higher. It is also a level that damages hearing in minutes — how many minutes is its own calculator.
| Source | Price | Headroom, MACH 20 | Headroom, Pro X10 | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 20.0 dB | 26.5 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 28.3 dB | 37.6 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 25.2 dB | 34.5 dB | 0.6 Ω | 1.0 µV |
Of the 280 sources here, 280 reach 100 dB on both. That is the easy axis. 42 of them also publish an output impedance low enough for both under the one-eighth rule and a noise figure that stays below the audible-hiss threshold with both — the rest either fail one of those or never printed the number at all, and 208 of them are in the second group.
The cheapest of the 42 is the JadeAudio JA11, at $20. It leaves 20.0 dB of headroom on the MACH 20 and 26.5 dB on the Pro X10, its output impedance is 0.5 Ω against a one-eighth limit of 12.00 Ω and 2.38 Ω, and its noise figure puts the hiss floor 15 dB and 4 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
Cheapest that satisfies three published numbers is not the same as best, and none of it is about how either headphone sounds. To put either model against a source this page does not mention, or to change the target loudness, use the amplifier matcher.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| MACH 20 | 20Hz – 18kHz | not printed | not printed |
| Pro X10 | 20Hz - 16kHz | not printed | not printed |
Westone prints 20Hz – 18kHz for the MACH 20 and 20Hz - 16kHz for the Pro X10.
Pro X10: The figure stands on Westone’s own spec sheet, not on the product page, which prints no frequency row at all.
Neither range has a tolerance printed beside it, and that is the whole of what this section can tell you. A wider range on one sheet is not deeper bass or more treble on that headphone: without a tolerance, neither number says how loud either model is at the ends of its own range, so the difference between the two is a difference between two pieces of marketing copy. A ±dB figure is what turns a range into a specification, and of the 490 models whose maker prints a range, 58 print it.
None of this is a measurement. What each maker publishes, and what it is worth, is set out in the frequency response audit.
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 20 and Westone Pro X10. 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.