Short answer
Both are portable players, $1799 against $1399.
The FiiO M27 reaches 100 dB on 567 of the 567 models here, the Sony NW-WM1AM2 on 552.
| Specification | FiiO M27 | Sony NW-WM1AM2 |
|---|---|---|
| Power into 32Ω | 1.8 W | 30 mW |
| Power into 150Ω | 391 mW | 6.4 mW |
| Power into 300Ω | 200 mW | 3.2 mW |
| Power into 600Ω | 100 mW | 1.6 mW |
| Output impedance | 0.5 Ω | 1 Ω unverified |
| Output noise | 3.9 µV | 3 µV unverified |
| Price | $1799 | $1399 |
| Headphones it reaches 100 dB on out of 567 | 567 | 552 |
| Balanced | FiiO M27 | Sony NW-WM1AM2 |
|---|---|---|
| Socket | 4.4mm | 4.4mm |
| Power into 32Ω | 5.0 W | 125 mW derived |
| Power into 300Ω | 805 mW | 13 mW derived |
| Output impedance | 0.6 Ω | not published |
| Output noise | 7.6 µV | not published |
| Headphones it reaches 100 dB on out of 567 | 567 | 561 |
Through the balanced sockets the FiiO M27 reaches 100 dB on 567 of the 567 models here and the Sony NW-WM1AM2 on 561. Derived figures are worked out from the loads the maker did publish.
| Load | FiiO M27 | Sony NW-WM1AM2 |
|---|---|---|
| 32 Ω | Published | Derived |
| 150 Ω | Derived | Derived |
| 300 Ω | Published | Derived |
| 600 Ω | Derived | Derived |
Only one of these two columns starts from a power rating. FiiO M27 publishes one at 32 Ω and at 300 Ω; Sony NW-WM1AM2 publishes none at any of these four loads, so its column is worked out from power it published at other loads. Both are arithmetic on a maker’s own figures rather than guesses, and the method used for the Sony NW-WM1AM2 understates rather than flatters — but at 32 Ω and at 300 Ω are the only loads here at which its maker can be held to a figure.
15 headphones reach 100 dB on the FiiO M27 but not on the Sony NW-WM1AM2 — Beyerdynamic DT 880 Edition (600Ω), Beyerdynamic DT 990 Edition (600Ω), HiFiMAN HE-6se V2, 12 more.
552 of the 567 models here reach 100 dB on both.
Headroom is at a 100 dB SPL peak.
The widest gap on the list is the Sennheiser HD 600: FiiO M27 has +15 dB of headroom there against -3 dB. 18 dB is about 63 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for Sony NW-WM1AM2 because that maker publishes no output noise figure.
| Headphone | Impedance | Needs | FiiO M27 headroom | Sony NW-WM1AM2 headroom | FiiO M27 hiss | Sony NW-WM1AM2 hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +46 dB | +29 dB | 26 dB | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +26 dB | +9 dB | 6 dB | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +30 dB | +12 dB | 4 dB | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +26 dB | +8 dB | -0 dB | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +24 dB | +7 dB | -1 dB | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +19 dB | +1 dB | -7 dB | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +15 dB | -3 dB | -11 dB | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | +13 dB | -5 dB | -13 dB | not published |
The FiiO M27 costs $400 more than the Sony NW-WM1AM2. Out of the 567 models here, that difference buys 15 more models driven to 100 dB.
Nothing runs the other way: there is no axis here on which the cheaper of the two does better.
Only published figures count here; blank axes are counted separately.
Each in full: FiiO M27 and Sony NW-WM1AM2.