The Audio-Technica ATH-A900Z is 44Ω at 100.0 dB/mW; the Audio-Technica ATH-R70X is 470Ω at 98.0 dB/mW. This page covers what they ask of an amplifier, not how they sound.
The ATH-R70X needs 2.0 dB more than the ATH-A900Z to reach the same loudness — 1.6 mW against 1.0 mW.
| Specification | ATH-A900Z | ATH-R70X |
|---|---|---|
| Impedance | 44 Ω | 470 Ω |
| Sensitivity | 100.0 dB/mW | 98.0 dB/mW |
| Sensitivity (voltage) | 113.6 dB/V | 101.3 dB/V |
| Power for 100 dB | 1.0 mW | 1.6 mW |
| Voltage for 100 dB | 0.21 V | 0.86 V |
| Current for 100 dB | 4.8 mA | 1.8 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 5.50 Ω | 58.75 Ω |
| Sources that reach 100 dB out of 280 | 280 | 277 |
3 of the 280 sources have the power for the ATH-A900Z but not for the ATH-R70X — Apple USB-C dongle (EU), Steinberg UR22C, Sony NW-A306.
32 sources are low enough in output impedance for the ATH-R70X under the one-eighth rule but not for the ATH-A900Z (Zoom AMS-22, Audient EVO 4, ART HeadAmp 4 Pro, 29 more).
1 source stays below the audible-hiss threshold with the ATH-R70X but crosses it with the ATH-A900Z (Schiit Mjolnir 3).
277 of the 280 sources here reach 100 dB on both.
The ATH-R70X is more demanding than 96% of the 567 non-electrostatic models in this database; the ATH-A900Z than 60%.
| dB SPL | ATH-A900Z power | ATH-A900Z voltage | ATH-R70X power | ATH-R70X voltage |
|---|---|---|---|---|
| 80 | 0.01 mW | 21 mV | 0.02 mW | 86 mV |
| 85 | 0.03 mW | 37 mV | 0.05 mW | 0.15 V |
| 90 | 0.10 mW | 66 mV | 0.16 mW | 0.27 V |
| 95 | 0.32 mW | 0.12 V | 0.50 mW | 0.49 V |
| 100 | 1.0 mW | 0.21 V | 1.6 mW | 0.86 V |
| 105 | 3.2 mW | 0.37 V | 5.0 mW | 1.53 V |
| Source | Price | Headroom, ATH-A900Z | Headroom, ATH-R70X | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 13.4 dB | 1.1 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 21.6 dB | 9.5 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR11 | $36 | 13.4 dB | 0.8 dB | 0.5 Ω | 8.0 µV |
Of the 280 sources here, 277 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 13.4 dB of headroom on the ATH-A900Z and 1.1 dB on the ATH-R70X, its output impedance is 0.5 Ω against a one-eighth limit of 5.50 Ω and 58.75 Ω, and its noise figure puts the hiss floor 22 dB and 34 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-A900Z | 5～40,000Hz | not printed | not printed |
| ATH-R70X | 5 - 40,000 Hz | not printed | not printed |
Audio-Technica prints 5～40,000Hz for the ATH-A900Z and 5 - 40,000 Hz for the ATH-R70X.
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-A900Z and Audio-Technica ATH-R70X. Every figure on this page comes from what Audio-Technica published, or is derived from it — what that maker publishes, counted.