The Audio-Technica ATH-R70xa is 470Ω with a sensitivity of 97.0 dB/mW, which is 100.3 dB/V. To reach 100 dB SPL — genuinely loud, louder than most people listen — it needs 2.0 mW, or 0.97 V across the drivers.
That is a moderate load. Most USB dongles handle it without complaint; the weakest phone outputs will run out of volume before they run out of quality. 261 of 280 sources here have enough headroom. The cheapest portable source that does the job is the Generic CX31993 dongles at $12.
Sensitivity here is in dB per milliwatt. Why the unit matters.
Audio-Technica publishes this directly as 97 dB/mW (1 mW (implied by the /mW unit; no frequency stated)), per milliwatt, so nothing was converted.
Source: audio-technica.com. How this data was built.
| As it is labelled | As printed | Tolerance | Standard |
|---|---|---|---|
| Frequency Response | 5 to 40,000 Hz | not printed | not printed |
Audio-Technica prints 5 to 40,000 Hz for the Audio-Technica ATH-R70xa, under the heading “Frequency Response”. Source: audio-technica.com.
No tolerance is printed with it, so “5 to 40,000 Hz” says nothing about how loud this headphone actually is at 5 Hz.
Only what the maker printed; maker by maker.
| Level | What it is | Power | Voltage | Current |
|---|---|---|---|---|
| 85 dB SPL | quiet background listening | 0.06 mW | 0.17 V | 0.4 mA |
| 95 dB SPL | normal listening | 0.63 mW | 0.54 V | 1.2 mA |
| 100 dB SPL | loud listening | 2.0 mW | 0.97 V | 2.1 mA |
| 105 dB SPL | very loud | 6.3 mW | 1.72 V | 3.7 mA |
| 110 dB SPL | peaks on dynamic music | 20 mW | 3.06 V | 6.5 mA |
Most people listen between 75 and 85 dB; the 100 dB row leaves room for peaks.
The 15 cheapest of the 280 sources here that reach 100 dB SPL into 470Ω with at least 10 dB of headroom and no known hiss or output-impedance problem with these headphones. All 280 sources, judged for these headphones.
| Source | Type | Price | Power into 470Ω | Headroom | Verdict |
|---|---|---|---|---|---|
| JDS Labs Atom+ (2nd gen) | desktop amplifier | $99 | 174 mW | +19 dB | Comfortable |
| Schiit Magni Heresy | desktop amplifier | $99 | 269 mW | +21 dB | Comfortable |
| Schiit Magni+ | desktop amplifier | $109 | 166 mW | +19 dB | Comfortable |
| Schiit Magni Unity | desktop amplifier | $119 | 274 mW | +21 dB | Comfortable |
| JDS Labs Atom Amp 2 | desktop amplifier | $129 | 182 mW | +20 dB | Comfortable |
| ART HeadAmp 4 Pro | desktop amplifier | $130 | 21 mW | +10 dB | Comfortable |
| Tanchjim LUNA | USB dongle | $140 | 34 mW | +12 dB | Comfortable |
| FiiO K11 | desktop DAC/amp | $143 | 38 mW | +13 dB | Comfortable |
| Schiit Vali 3 | desktop amplifier | $149 | 255 mW | +21 dB | Comfortable |
| Topping L30 II | desktop amplifier | $149 | 357 mW | +23 dB | Comfortable |
| SMSL HO100 | desktop amplifier | $160 | 128 mW | +18 dB | Comfortable |
| Shanling H2 | portable amplifier | $169 | 46 mW | +14 dB | Comfortable |
| xDuoo MT-604 | desktop amplifier | $169 | 136 mW | +18 dB | Comfortable |
| FiiO K11 R2R | desktop DAC/amp | $176 | 32 mW | +12 dB | Comfortable |
| Little Dot MK II | desktop amplifier | $176 | 191 mW | +20 dB | Comfortable |
Hiss. At 100.3 dB/V these are sensitive enough to reveal a source's own noise floor. The noisiest source in the database, the Schiit Mjolnir 3, would put its hiss at roughly 8 dB SPL in these headphones — faintly audible in a silent room. Check your own source.
Output impedance. At 470Ω these want a source output impedance below 58.75Ω to satisfy the one-eighth rule; 2 of the 192 sources that publish one miss it. Check yours here.
470Ω · 98.0 dB/mW · Moderate
See requirements →420Ω · 100.0 dB/mW · Moderate
See requirements →50Ω · 98.0 dB/mW · Easy
See requirements →120Ω · 91.8 dB/mW · Moderate
See requirements →50Ω · 88.0 dB/mW · Moderate
See requirements →45Ω · 86.0 dB · Moderate
See requirements →Compared with its stablemates: vs ATH-A2000Z · vs ATH-A900Z · vs ATH-A990Z · vs ATH-AD1000X · vs ATH-AD700X · vs ATH-AD900X · vs ATH-ADX3000 · vs ATH-ADX5000 · vs ATH-AWKG · vs ATH-GDL3 · vs ATH-GL3 · vs ATH-M20x · vs ATH-M30X · vs ATH-M40X · vs ATH-M50X · vs ATH-M50xBT2 (wired) · vs ATH-M60x · vs ATH-M70X · vs ATH-R50x · vs ATH-R70X · vs ATH-W1000Z · vs ATH-WP900.