Sony NW-WM1AM2: power output and what it will drive

The Sony NW-WM1AM2 is a portable player at $1399. It delivers 30 mW into 32Ω and 3.2 mW into 300Ω, which ranks it 264 of 280 for raw power among the sources in this database.

Measured at 100 dB SPL it has comfortable headroom on 422 of the 567 dynamic and planar headphones catalogued here, enough but not generous on 102, only marginal on 28 and not enough power for 15. Sony house sound and excellent refinement, with moderate power.

The manufacturer publishes 60 mW into 16Ω. Everything else in the table above is worked out from those figures, and this table says which is which.

The balanced output is rated separately: 125 mW into 32Ω through the 4.4mm jack.

Derivation holds output voltage steady between and beyond the published loads rather than output power, because that is what an amplifier actually does. The full method is written up here.

The output impedance or output noise shown above did not turn up in any manufacturer document during this check. It is carried over from the material this database was first built from, and is marked unverified rather than quietly presented as sourced.

Source: sony-asia.com, sony.co.uk, helpguide.sony.net.

Ordered from easiest to hardest to drive. Headroom is measured at 100 dB SPL, which is louder than almost anyone listens — a small negative number means the source still plays loud, just without reserve for peaks.

These figures come from each manufacturer's own sensitivity rating. A handful of planars — the HiFiMAN Susvara and the Abyss AB-1266 in particular — are widely reported to need far more than their published sensitivity implies, so treat a bare pass on those as optimistic rather than settled.

At 3 µV of output noise, here is where that noise lands in the five most revealing in-ears in the database.

That noise figure has not been traced to a document from the maker, so the levels below are as good as the number they start from.

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 1Ω output impedance, the one-eighth rule says this source suits headphones of 8.0Ω and above. 15 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.

That output impedance has not been traced to a document from the maker, so the count above is only as good as the number it starts from.

The rule is a rule of thumb, not physics: a source impedance below one eighth of the headphone's keeps the interaction under about 1 dB. The checker works it out for any pair.

On every figure Sony publishes for this headphone output, the Sony NW-WM1AM2 is identical to the Sony NW-WM1ZM2. Each of them states power at 16 Ω — and each states the same values.

They do not cost the same. The spread across the 2 of them is $2301, and none of that difference is visible in the figures above.

Identical published figures do not mean identical products. A spec sheet for a headphone output covers power, output impedance and noise. It says nothing about the converter, the inputs, the case, the battery, the volume control or how any of it sounds, and those are real differences that cost real money. What this section says is narrower and worth saying anyway: if you are choosing between these on what the maker printed about the headphone jack, there is nothing to choose.

15 groups of products in this database share a spec sheet this way, 36 products in all.

Of the 280 sources here, 173 do everything the Sony NW-WM1AM2 does as a headphone output: reach 100 dB on every headphone it reaches. The cheapest of them is the FiiO SnowSky Tiny B at $22, against this one’s $1399 — $1377 less, and a USB dongle rather than a portable player.

The cheaper one also publishes an output impedance, which the Sony NW-WM1AM2 does not — so on the paperwork it is ahead, not merely level.

This counts a headphone output and nothing else. Inputs, converters, microphone preamps, balanced outputs, the volume control, the case and the warranty are all outside it, and any of them can be the reason to buy the dearer box. What the count does say is that the three numbers a maker can be held to do not separate them.

Worked out in advance against its closest rivals: vs FiiO M17 · vs FiiO M27 · vs iBasso DX340 · vs Lotoo PAW 6000 · vs Shanling M7 · vs Sony NW-A306 · vs Sony NW-ZX707. Each of those pages lists the headphones that tell the two apart.

Or put any two side by side in the source comparison tool, or run your own headphones through the amplifier matcher. Or see every Sony source in the database, and how much of what this site says about them came from Sony’s own documents.