Short answer
Both are portable players, both at $1799.
On raw power they are level: each reaches 100 dB on 567 of the 567 non-electrostatic models here.
| Specification | FiiO M17 | FiiO M27 |
|---|---|---|
| Power into 32Ω | 500 mW | 1.8 W |
| Power into 150Ω | 115 mW | 391 mW |
| Power into 300Ω | 63 mW | 200 mW |
| Power into 600Ω | 32 mW | 100 mW |
| Output impedance | 1 Ω | 0.5 Ω |
| Output noise | 3.5 µV | 3.9 µV |
| Price | $1799 | $1799 |
| Headphones it reaches 100 dB on out of 567 | 567 | 567 |
| Balanced | FiiO M17 | FiiO M27 |
|---|---|---|
| Socket | 4.4mm | 4.4mm |
| Power into 32Ω | 3.0 W | 5.0 W |
| Power into 300Ω | 250 mW | 805 mW |
| Output impedance | 2 Ω | 0.6 Ω |
| Output noise | 7 µV | 7.6 µV |
| Headphones it reaches 100 dB on out of 567 | 567 | 567 |
Through the balanced sockets the two are level on the same test: each reaches 100 dB on 567 of the 567 models here.
| As published | FiiO M17 | FiiO M27 |
|---|---|---|
| DAC | Dual ES9038PRO (ES9038PRO x2) | Dual ES9039SPRO (ES9039SPRO x2) |
| Processor | Qualcomm Snapdragon 660 | Qualcomm Dragonwing QCS6490 |
| Operating system | Android 10 | Android (version not stated); modes: Android / Pure music / AirPlay / USB DAC / Bluetooth receiving / Coaxial decoding |
| Storage | 64 GB storage (about 46 GB available), 4 GB RAM, single TF card slot up to 2 TB (theoretical) | 256 GB storage (about 241 GB free), 8 GB RAM, dual microSD (TF) up to 4 TB total (2 TB per card, theoretical) |
| Outputs | 3.5 mm single-ended + 6.35 mm single-ended + 2.5 mm balanced + 4.4 mm balanced; 3.5 mm line out (shared PO); coaxial | 3.5 mm + 6.35 mm headphone out, 4.4 mm balanced out, line out on 3.5 mm + 6.35 mm (shared PO), RCA coaxial out, RCA coaxial in |
| Bluetooth | Bluetooth 5.0; transmit SBC/AAC/aptX/aptX HD/LDAC/LHDC; receive SBC/AAC/aptX/aptX Low Latency/aptX HD/aptX Adaptive/LDAC | Transmit Bluetooth 5.2: SBC/AAC/aptX/aptX HD/aptX Adaptive/LDAC/LHDC; receive Bluetooth 5.4: SBC/AAC/aptX/aptX Lossless/aptX HD/aptX Adaptive/LDAC |
| Wi-Fi | 2.4 GHz / 5 GHz, DLNA, AirPlay, Wi-Fi music transfer, Roon Ready | 2.4 GHz / 5 GHz, DLNA, AirPlay, Wi-Fi song transmission |
| Formats | Local playback up to 384kHz-32bit / DSD256; USB DAC up to 768kHz-32bit / DSD512 (Native) | Local decoding up to 768kHz/32bit, DSD512 (Native); USB audio 768kHz/32bit, DSD512 |
| Screen | 5.99-inch, 1080 x 2160, incell fully laminated | 5.99-inch, 1080 x 2160, bezel-less |
| Battery | 9200 mAh | 9200 mAh |
| Battery life | >10 h (3.5 mm headphone output) / >8 h (2.5 mm + 4.4 mm balanced output) | 9 h (3.5 mm / 6.35 mm headphone output) / 8 h (4.4 mm balanced) |
| Weight | 610 g | 556 g (black) / 630 g (titanium) |
| Dimensions | About 156.4 x 88.5 x 28 mm | About 157.4 x 85.1 x 28 mm |
Copied from the makers’ own pages: fiio.com/m17, fiio.com/M17_parameters, fiio.com/m27, fiio.com/m27_parameters. Battery life is the maker’s own test figure.
| Load | FiiO M17 | FiiO M27 |
|---|---|---|
| 32 Ω | Published | Published |
| 150 Ω | Derived | Derived |
| 300 Ω | Published | Published |
| 600 Ω | Derived | Derived |
Both makers publish a power rating. FiiO M17 publishes at 32 Ω and at 300 Ω; FiiO M27 at 32 Ω and at 300 Ω. The other rows are worked out from those.
The two publish at the same loads, which is the one case where the rows of this table can be read straight across.
On power they are interchangeable across this whole database: there is no headphone here that one reaches 100 dB on and the other does not.
14 headphones are left alone by the FiiO M27 under the one-eighth rule but coloured by the FiiO M17 (64 Audio Nio, 64 Audio Volur, Campfire Audio Andromeda 2023, 11 more).
10 headphones stay below the audible-hiss threshold on the FiiO M17 but cross it on the FiiO M27 (Austrian Audio Hi-X25BT, Beyerdynamic DJ 300 PRO X, Hidizs MS2 PRO, 7 more).
567 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 HiFiMAN HE400se: FiiO M27 has +24 dB of headroom there against +19 dB. 6 dB is about 3.6 times the power, which matters for peaks rather than for how loud the music sits.
Hiss below about 20 dB SPL is inaudible in a quiet room.
| Headphone | Impedance | Needs | FiiO M17 headroom | FiiO M27 headroom | FiiO M17 hiss | FiiO M27 hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +40 dB | +46 dB | 25 dB | 26 dB |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +20 dB | +26 dB | 5 dB | 6 dB |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +25 dB | +30 dB | 3 dB | 4 dB |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +21 dB | +26 dB | -1 dB | -0 dB |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +19 dB | +24 dB | -2 dB | -1 dB |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +14 dB | +19 dB | -8 dB | -7 dB |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +10 dB | +15 dB | -12 dB | -11 dB |
| HiFiMAN Susvara | 60 Ω | 50 mW | +7 dB | +13 dB | -14 dB | -13 dB |
These two cost the same, $1799, so price settles nothing. Out of the 567 models here, the FiiO M17 keeps 10 models below the audible-hiss threshold; the FiiO M27 leaves 14 models alone under the one-eighth rule — and that is the whole of it on these three axes.
Only published figures count here; blank axes are counted separately.