On power, yes — all of them. Every one of the 39 portable players in this database reaches 100 dB SPL on the Audio-Technica ATH-M40X, which needs 1.6 mW at its 35Ω.
Power is one of three questions and the one that goes wrong least often. The other two — whether the source’s output impedance leaves the frequency response alone, and whether you will hear its noise floor — are answered further down, separately, because a source can pass one and fail another.
The cheapest one that does reach it is the Hidizs AP80 Pro Max at $179, which delivers 64 mW into 35Ω — 16 dB of headroom over the 1.6 mW this headphone needs for 100 dB SPL.
100 dB SPL is a peak level, not a listening level. If you listen at 85 dB the same headphone needs 0.05 mW, which is 15 dB less, and the answer above changes for most of the category. The model page has the full ladder.
Under the one-eighth rule the Audio-Technica ATH-M40X wants a source below 4.38Ω. Of the 26 portable players here that publish an output impedance, 25 are under it and 1 are not.
The furthest over is the Shanling H5 at 4.7Ω, which is 1× the ceiling. Above that threshold the source stops being a volume control and starts being part of the frequency response. The simulator shows what that looks like.
The other 13 publish nothing at all on this, so they are not on either side of that count. This site leaves them blank rather than assuming a figure.
Hiss depends on the source’s own noise floor and on how sensitive the headphone is. At 98.0 dB/mW and 35Ω, the Audio-Technica ATH-M40X turns one microvolt of source noise into about -7 dB SPL — and the threshold where that stops being noticeable in a quiet room is around 20 dB SPL.
Of the 12 portable players here that publish a noise figure, 12 stay below that threshold with this headphone and 0 cross it.
The remaining 27 publish no noise figure, so they cannot be placed on either side.
| Source | Price | Into 35 Ω | Headroom | Output impedance | Hiss in these |
|---|---|---|---|---|---|
| FiiO JM21 | $199 | 224 mW | 21.5 dB | 1 Ω | -3 dB SPL |
| FiiO M11S | $499 | 183 mW | 20.6 dB | 1.5 Ω | -2 dB SPL |
| FiiO M21 | $599 | 370 mW | 23.7 dB | 1.0 Ω | -1 dB SPL |
11 of the 39 portable players here publish all three figures. 11 of those clear all three for the Audio-Technica ATH-M40X, and the cheapest is the FiiO JM21 at $199.
It delivers 224 mW into 35 Ω where this headphone needs 1.6 mW for 100 dB — 21.5 dB of headroom — its output impedance of 1 Ω sits under the one-eighth ceiling of 4.38 Ω, and its 1.6 µV of noise leaves the hiss 23 dB under the 20 dB SPL threshold this site uses.
Cheapest that satisfies three published numbers is not the same as best, and the sources left out of this count are left out for want of a published figure, not for failing one. How often that happens is its own page.
| Source | Price | Into 35Ω | Output impedance | Hiss in these | Power verdict |
|---|---|---|---|---|---|
| Hidizs AP80 Pro Max | $179 | 64 mW | not published | not published | Comfortable |
| TempoTec Variations V3 Blaze | $179 | 754 mW | not published | not published | Comfortable |
| Surfans F28 | $180 | 114 mW | not published | not published | Comfortable |
| Hidizs AP80 Pro-X | $189 | 64 mW | not published | not published | Comfortable |
| FiiO JM21 | $199 | 224 mW | 1 Ω | -3 dB SPL | Comfortable |
| Shanling M1 Plus | $209 | 178 mW | 0.6 Ω | not published | Comfortable |
| Moondrop DISCDREAM2 ULTRA | $350 | 102 mW | not published | not published | Comfortable |
| Sony NW-A306 | $350 | 16 mW | not published | not published | Comfortable |
| TempoTec Variations V6 | $369 | 302 mW | not published | not published | Comfortable |
| Shanling M3 Ultra | $479 | 128 mW | 1 Ω | not published | Comfortable |
| iBasso DX180 | $480 | 240 mW | 0.6 Ω | not published | Comfortable |
| FiiO M11S | $499 | 183 mW | 1.5 Ω | -2 dB SPL | Comfortable |
Sorted by how many of the three questions the source answers well, then by price. A blank in a column is a blank in the manufacturer’s own documentation, not a zero.
The Audio-Technica ATH-M40X on other categories: desktop amplifiers · desktop DAC/amps · audio interfaces.
The Audio-Technica ATH-M40X page has every source in the database against this headphone, and the matcher takes your own numbers.