The Audio-Technica ATH-M20x is 47Ω at 96.0 dB (no reference unit printed); the Audio-Technica ATH-R70xa is 470Ω at 97.0 dB/mW. This page covers what they ask of an amplifier, not how they sound.
The ATH-M20x needs 1.0 dB more than the ATH-R70xa to reach the same loudness — 2.5 mW against 2.0 mW.
| Specification | ATH-M20x | ATH-R70xa |
|---|---|---|
| Impedance | 47 Ω | 470 Ω |
| Sensitivity | 96.0 dB | 97.0 dB/mW |
| Sensitivity (voltage) | 109.3 dB/V | 100.3 dB/V |
| Power for 100 dB | 2.5 mW | 2.0 mW |
| Voltage for 100 dB | 0.34 V | 0.97 V |
| Current for 100 dB | 7.3 mA | 2.1 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 5.88 Ω | 58.75 Ω |
| Sources that reach 100 dB out of 280 | 280 | 275 |
One caution before reading the rows. Audio-Technica ATH-M20x 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.
5 of the 280 sources have the power for the ATH-M20x but not for the ATH-R70xa — Apple USB-C dongle (EU), FiiO BTR11, Steinberg UR22C, 2 more.
32 sources are low enough in output impedance for the ATH-R70xa under the one-eighth rule but not for the ATH-M20x (Zoom AMS-22, Audient EVO 4, ART HeadAmp 4 Pro, 29 more).
275 of the 280 sources here reach 100 dB on both.
The ATH-R70xa is more demanding than 98% of the 567 non-electrostatic models in this database; the ATH-M20x than 78%.
| dB SPL | ATH-M20x power | ATH-M20x voltage | ATH-R70xa power | ATH-R70xa voltage |
|---|---|---|---|---|
| 80 | 0.03 mW | 34 mV | 0.02 mW | 97 mV |
| 85 | 0.08 mW | 61 mV | 0.06 mW | 0.17 V |
| 90 | 0.25 mW | 0.11 V | 0.20 mW | 0.31 V |
| 95 | 0.79 mW | 0.19 V | 0.63 mW | 0.54 V |
| 100 | 2.5 mW | 0.34 V | 2.0 mW | 0.97 V |
| 105 | 7.9 mW | 0.61 V | 6.3 mW | 1.72 V |
| Source | Price | Headroom, ATH-M20x | Headroom, ATH-R70xa | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 9.1 dB | 0.1 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 17.3 dB | 8.5 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 14.3 dB | 5.1 dB | 0.6 Ω | 1.0 µV |
Of the 280 sources here, 275 reach 100 dB on both. 69 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 cheapest of the 69 is the JadeAudio JA11, at $20. It leaves 9.1 dB of headroom on the ATH-M20x and 0.1 dB on the ATH-R70xa, its output impedance is 0.5 Ω against a one-eighth limit of 5.88 Ω and 58.75 Ω, and its noise figure puts the hiss floor 26 dB and 35 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| ATH-M20x | 15 - 20,000 Hz | not printed | not printed |
| ATH-R70xa | 5 to 40,000 Hz | not printed | not printed |
Audio-Technica prints 15 - 20,000 Hz for the ATH-M20x and 5 to 40,000 Hz for the ATH-R70xa.
Neither range has a tolerance printed beside it, so a wider range on one sheet is not deeper bass or more treble.
Not a measurement; maker by maker.
Both have a page of their own. In full: Audio-Technica ATH-M20x and Audio-Technica ATH-R70xa. Each figure on this page is labelled on those pages with where it came from, including the ones Audio-Technica never published — what that maker publishes, counted.