The Audio-Technica ATH-R70X is 470Ω at 98.0 dB/mW; the Dan Clark Audio Expanse is 26Ω at 90.0 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 Dan Clark Audio Expanse needs 8.0 dB more than the Audio-Technica ATH-R70X to reach the same loudness — 10 mW against 1.6 mW.
| Specification | Audio-Technica ATH-R70X | Dan Clark Audio Expanse |
|---|---|---|
| Impedance | 470 Ω | 26 Ω |
| Sensitivity | 98.0 dB/mW | 90.0 dB/mW |
| Sensitivity (voltage) | 101.3 dB/V | 105.9 dB/V |
| Power for 100 dB | 1.6 mW | 10 mW |
| Voltage for 100 dB | 0.86 V | 0.51 V |
| Current for 100 dB | 1.8 mA | 19.6 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 58.75 Ω | 3.25 Ω |
| Sources that reach 100 dB out of 280 | 277 | 279 |
2 of the 280 sources have the power for the Dan Clark Audio Expanse but not for the Audio-Technica ATH-R70X — Apple USB-C dongle (EU), Sony NW-A306.
33 sources are low enough in output impedance for the Audio-Technica ATH-R70X under the one-eighth rule but not for the Dan Clark Audio Expanse (Zoom AMS-22, Audient EVO 4, ART HeadAmp 4 Pro, 30 more).
277 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 Audio-Technica ATH-R70X is more demanding than 96% of the 567 non-electrostatic models in this database; the Dan Clark Audio Expanse than 87%. 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 | Audio-Technica ATH-R70X power | Audio-Technica ATH-R70X voltage | Dan Clark Audio Expanse power | Dan Clark Audio Expanse voltage |
|---|---|---|---|---|
| 80 | 0.02 mW | 86 mV | 0.10 mW | 51 mV |
| 85 | 0.05 mW | 0.15 V | 0.32 mW | 91 mV |
| 90 | 0.16 mW | 0.27 V | 1.0 mW | 0.16 V |
| 95 | 0.50 mW | 0.49 V | 3.2 mW | 0.29 V |
| 100 | 1.6 mW | 0.86 V | 10 mW | 0.51 V |
| 105 | 5.0 mW | 1.53 V | 32 mW | 0.91 V |
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, Audio-Technica ATH-R70X | Headroom, Dan Clark Audio Expanse | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 1.1 dB | 3.9 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 9.5 dB | 13.2 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR11 | $36 | 0.8 dB | 5.2 dB | 0.5 Ω | 8.0 µV |
Of the 280 sources here, 277 reach 100 dB on both. That is the easy axis. 70 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 205 of them are in the second group.
The cheapest of the 70 is the JadeAudio JA11, at $20. It leaves 1.1 dB of headroom on the Audio-Technica ATH-R70X and 3.9 dB on the Dan Clark Audio Expanse, its output impedance is 0.5 Ω against a one-eighth limit of 58.75 Ω and 3.25 Ω, and its noise figure puts the hiss floor 34 dB and 30 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 |
|---|---|---|---|
| Audio-Technica ATH-R70X | 5 - 40,000 Hz | not printed | not printed |
| Dan Clark Audio Expanse | “Yes, it has one” | not printed | not printed |
Audio-Technica prints 5 - 40,000 Hz for the ATH-R70X. Dan Clark Audio prints “Yes, it has one” for the Expanse.
Dan Clark Audio Expanse: The specification table has a frequency-response row. The value printed in it is the sentence "Yes, it has one".
One of these two sheets prints a range and the other prints a sentence declining to, and the second is the more informative of the two. The range given for the Audio-Technica ATH-R70X carries no tolerance, so it says nothing about how loud that model is at either end of it — which is exactly the objection the other sheet is making out loud.
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: Audio-Technica ATH-R70X and Dan Clark Audio Expanse. Every figure on this page comes from what Audio-Technica and Dan Clark Audio published, or is derived from it — what Audio-Technica publishes and what Dan Clark Audio publishes, both counted.