FiiO M15S: power output and what it will drive

The FiiO M15S is a portable player at $799. It delivers 580 mW into 32Ω and 93 mW into 300Ω, which ranks it 99 of 280 for raw power among the sources in this database.

Measured at 100 dB SPL it has comfortable headroom on 556 of the 567 dynamic and planar headphones catalogued here, enough but not generous on 10 and not enough power for 1. Power is published at 16Ω, 32Ω, 300Ω; the rest of the table is derived from those figures.

The manufacturer publishes 535 mW into 16Ω, 580 mW into 32Ω, 93 mW into 300Ω. The rest of the table is worked out from those.

The balanced output is rated separately: 1.2 W into 32Ω through the 4.4mm (2.5mm also provided) jack.

Derived rows hold output voltage steady, as an amplifier does (method).

Source: fiio.com.

Easiest to hardest to drive, with headroom at a 100 dB SPL peak.

At 3.2 µV of output noise, here is where that noise lands in the five most revealing in-ears in the database.

This one hisses. With the most sensitive in-ears in the database its own noise lands around 31 dB SPL, which you will hear between tracks and in quiet passages.

At 1.4Ω output impedance, the one-eighth rule says this source suits headphones of 11.2Ω and above. 51 of the 567 models here fall below that. Most of them are multi-driver in-ears, and the mismatch tilts the frequency response audibly rather than subtly.

Check any pair.

Copied from the makers’ own pages: fiio.com/m15s_parameters, fiio.com/m15s. Battery life is the maker’s own test figure.

Of the 280 sources here, 28 do everything the FiiO M15S does as a headphone output: reach 100 dB on every headphone it reaches, stay inside the one-eighth rule wherever it does and stay under the audible-hiss threshold wherever it does. The cheapest of them is the FiiO KA11 at $29, against this one’s $799 — $770 less, and a USB dongle rather than a portable player.

This counts the headphone output only; inputs, converters, the volume control and the build are outside it.

Compared with its closest rivals: vs Astell&Kern SR35 · vs Cayin N3 Ultra · vs FiiO JM21 · vs FiiO M11S · vs FiiO M17 · vs FiiO M21 · vs FiiO M23 · vs FiiO M27 · vs FiiO M33 R2R · vs HiBy RS6 · vs iBasso DX260 · vs iBasso DX260 MK2 · vs iBasso DX270 · vs Shanling M6 Ultra · vs Shanling M7 · vs Sony NW-ZX707.

Compare any two or match your own headphones. Every FiiO source here.