The Audio-Technica ATH-M20x is 47Ω. Its maker prints a sensitivity of 96.0 dB and never says whether that is per milliwatt or per volt, so this page reads it as per milliwatt — on that reading it needs 2.5 mW to reach 100 dB SPL, or 0.34 V across the drivers. If the figure is really per volt, it needs far more.
That puts it in the easy category. A phone, a laptop headphone jack or the cheapest USB dongle will drive it to painful levels. Of the 280 sources in the database, 259 have at least 10 dB of headroom and another 21 have enough. The cheapest portable source that does the job is the Apple USB-C dongle (US) at $9.
This maker printed a decibel figure and no reference unit, so the number above is shown exactly as printed. Everything below reads it as per milliwatt, which is the commoner convention on a sheet that omits the unit — if it is really per volt, this headphone is about 13 dB harder to drive than the rest of this page assumes. The converter explains the difference.
Audio-Technica publishes a sensitivity of 96 dB and does not state whether that is per milliwatt or per volt — the spec sheet simply stops at the number.
Both readings are given here so you can judge for yourself. If that 96 dB is per milliwatt, the figures on this page are right as they stand. If it is per volt, the real sensitivity is 82.7 dB/mW — 13 dB lower at 47Ω — and everything above understates what these need by that much. The per-milliwatt reading is the one shown, because it is the more common convention on a spec sheet that omits the unit; treat it as an indication rather than a specification.
Source: audio-technica.com, audio-technica.com. How this data was built.
| As it is labelled | As printed | Tolerance | Standard |
|---|---|---|---|
| Frequency Response | 15 - 20,000 Hz | not printed | not printed |
Audio-Technica prints 15 - 20,000 Hz for the Audio-Technica ATH-M20x, under the heading “Frequency Response”. Source: audio-technica.com.
No tolerance is printed with it, so “15 - 20,000 Hz” says nothing about how loud this headphone actually is at 15 Hz.
Only what the maker printed; maker by maker.
| Level | What it is | Power | Voltage | Current |
|---|---|---|---|---|
| 85 dB SPL | quiet background listening | 0.08 mW | 61 mV | 1.3 mA |
| 95 dB SPL | normal listening | 0.79 mW | 0.19 V | 4.1 mA |
| 100 dB SPL | loud listening | 2.5 mW | 0.34 V | 7.3 mA |
| 105 dB SPL | very loud | 7.9 mW | 0.61 V | 13.0 mA |
| 110 dB SPL | peaks on dynamic music | 25 mW | 1.09 V | 23.1 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 47Ω 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 47Ω | Headroom | Verdict |
|---|---|---|---|---|---|
| FiiO KA11 | USB dongle | $29 | 136 mW | +17 dB | Comfortable |
| Tanchjim Stargate II | USB dongle | $40 | 51 mW | +13 dB | Comfortable |
| ddHiFi TC35AL | USB dongle | $46 | 143 mW | +18 dB | Comfortable |
| ddHiFi TC35Air | USB dongle | $46 | 143 mW | +18 dB | Comfortable |
| Fosi Audio N3 | Bluetooth receiver | $50 | 94 mW | +16 dB | Comfortable |
| Hidizs SD2 | USB dongle | $50 | 48 mW | +13 dB | Comfortable |
| FiiO BTR13 | Bluetooth receiver | $59 | 68 mW | +14 dB | Comfortable |
| iFi GO link | USB dongle | $59 | 50 mW | +13 dB | Comfortable |
| Kiwi Ears Allegro Pro | USB dongle | $60 | 46 mW | +13 dB | Comfortable |
| ddHiFi TC35Pro (Mountain2) | USB dongle | $66 | 44 mW | +12 dB | Comfortable |
| iBasso DC03 Pro | USB dongle | $69 | 67 mW | +14 dB | Comfortable |
| DUNU DTC 480 | USB dongle | $70 | 44 mW | +12 dB | Comfortable |
| EPZ TP35 Pro | USB dongle | $70 | 76 mW | +15 dB | Comfortable |
| Tanchjim Space | USB dongle | $70 | 85 mW | +15 dB | Comfortable |
| Truthear SHIO | USB dongle | $70 | 85 mW | +15 dB | Comfortable |
Hiss. At 109.3 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 17 dB SPL in these headphones — clearly audible in quiet passages. Check your own source.
Output impedance. At 47Ω these want a source output impedance below 5.88Ω to satisfy the one-eighth rule; 34 of the 192 sources that publish one miss it. Check yours here.
47Ω · 96.0 dB/mW · Easy
See requirements →48Ω · 102.0 dB/mW · Easy
See requirements →45Ω · 98.0 dB/mW · Easy
See requirements →30Ω · 94.0 dB/mW · Easy
See requirements →48Ω · 96.0 dB/mW · Easy
See requirements →48Ω · 96.0 dB/mW · Easy
See requirements →Compared with its stablemates: vs ATH-A2000Z · vs ATH-AWKG · vs ATH-R70X · vs ATH-R70xa.