SMSL DO400: power output and what it will drive

The SMSL DO400 is a desktop DAC/amp at $520. It delivers 3.0 W into 32Ω and 700 mW into 300Ω, which ranks it 26 of 280 for raw power among the sources in this database.

Measured at 100 dB SPL it has comfortable headroom on 567 of the 567 dynamic and planar headphones catalogued here. DAC and headphone amp in one box, with XLR, 4.4 mm and 6.35 mm outputs sharing a single published power rating.

Specifications

What it actually puts out

TypeDesktop DAC/amp

Price$520

Power into 32 Ω3.0 W

Power into 150 Ω938 mW

Power into 300 Ω700 mW

Power into 600 Ω350 mW

Output impedance<0.1 Ω

Output noisenot published

Comfortable headroom on 567 of 567 headphones (100%)

Provenance

Where these numbers come from

The manufacturer publishes 6.0 W into 16Ω, 3.0 W into 32Ω, 700 mW into 300Ω, 350 mW into 600Ω. The rest of the table is worked out from those.

The published figures describe the balanced output. A single-ended jack on the same unit will put out less — usually about half the voltage and a quarter of the power.

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

Source: smsl-audio.com.

Load	Power	Status	How it was arrived at
16 Ω	6.0 W	Published	the manufacturer publishes this figure at this exact load
32 Ω	3.0 W	Published	the manufacturer publishes this figure at this exact load
150 Ω	938 mW	Derived	worked out between two published loads, holding output voltage linear between them
300 Ω	700 mW	Published	the manufacturer publishes this figure at this exact load
600 Ω	350 mW	Published	the manufacturer publishes this figure at this exact load

Matching

Against 40 well-known headphones

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

Headphone	Impedance	Sensitivity	Needs	Headroom	Verdict
Shure SE846	9 Ω	114.0 dB/mW	0.04 mW	+49 dB	Comfortable
64 Audio U12t	12.6 Ω	108.0 dB/mW	0.16 mW	+45 dB	Comfortable
Shure SE215	17 Ω	107.0 dB/mW	0.20 mW	+45 dB	Comfortable
Moondrop Aria	32 Ω	107.1 dB/mW	0.19 mW	+42 dB	Comfortable
Audeze LCD-X 2021	20 Ω	103.0 dB/mW	0.50 mW	+40 dB	Comfortable
Truthear Hexa	20.5 Ω	103.1 dB/mW	0.49 mW	+40 dB	Comfortable
Sennheiser IE 200	18 Ω	101.6 dB/mW	0.69 mW	+39 dB	Comfortable
Sony MDR-7506	63 Ω	106.0 dB/mW	0.25 mW	+38 dB	Comfortable
Meze 99 Classics	32 Ω	103.0 dB/mW	0.50 mW	+38 dB	Comfortable
Focal Clear MG	55 Ω	104.0 dB/mW	0.40 mW	+37 dB	Comfortable
Philips SHP9500	32 Ω	101.0 dB	0.79 mW	+36 dB	Comfortable
Focal Utopia	80 Ω	104.0 dB/mW	0.40 mW	+36 dB	Comfortable
Meze Empyrean	32 Ω	100.0 dB	1.0 mW	+35 dB	Comfortable
Campfire Audio Andromeda 2020	9 Ω	94.0 dB	4.0 mW	+29 dB	Comfortable
Etymotic ER2SE	15 Ω	96.0 dB/mW	2.5 mW	+34 dB	Comfortable
AKG K371	32 Ω	99.1 dB/mW	1.2 mW	+34 dB	Comfortable
Audio-Technica ATH-M50X	38 Ω	99.0 dB/mW	1.3 mW	+33 dB	Comfortable
Beyerdynamic DT 900 Pro X	48 Ω	100.0 dB/mW	1.0 mW	+33 dB	Comfortable
Audeze LCD-2 Classic	70 Ω	101.0 dB/mW	0.79 mW	+33 dB	Comfortable
Grado SR80x	38 Ω	98.0 dB/mW	1.6 mW	+32 dB	Comfortable
Sennheiser HD 560S	120 Ω	100.8 dB/mW	0.83 mW	+31 dB	Comfortable
HiFiMAN Edition XS	18 Ω	92.0 dB	6.3 mW	+29 dB	Comfortable
HiFiMAN Arya Stealth	32 Ω	94.0 dB	4.0 mW	+29 dB	Comfortable
Dan Clark Audio AEON 2 Closed	13 Ω	90.0 dB/mW	10 mW	+27 dB	Comfortable
Audeze LCD-5	14 Ω	90.0 dB/mW	10 mW	+27 dB	Comfortable
Beyerdynamic DT 1990 Pro (250Ω)	250 Ω	102.0 dB/mW	0.63 mW	+31 dB	Comfortable
HiFiMAN HE400se	25 Ω	91.0 dB	7.9 mW	+27 dB	Comfortable
HiFiMAN Sundara	32 Ω	92.0 dB	6.3 mW	+27 dB	Comfortable
Dan Clark Audio Stealth	23 Ω	90.0 dB/mW	10 mW	+26 dB	Comfortable
Fostex T50RP MK3	50 Ω	92.0 dB/mW	6.3 mW	+25 dB	Comfortable
AKG K702	62 Ω	92.9 dB/mW	5.1 mW	+25 dB	Comfortable
ZMF Verite Closed	300 Ω	99.0 dB/mW	1.3 mW	+27 dB	Comfortable
Sennheiser HD 650	300 Ω	97.8 dB/mW	1.7 mW	+26 dB	Comfortable
Sennheiser HD 800S	300 Ω	96.8 dB/mW	2.1 mW	+25 dB	Comfortable
Beyerdynamic DT 770 Pro (250Ω)	250 Ω	96.0 dB	2.5 mW	+25 dB	Comfortable
Audio-Technica ATH-R70X	470 Ω	98.0 dB/mW	1.6 mW	+25 dB	Comfortable
ZMF Atrium	300 Ω	96.0 dB/mW	2.5 mW	+24 dB	Comfortable
Abyss AB-1266 Phi TC	50 Ω	88.0 dB/mW	16 mW	+21 dB	Comfortable
Sennheiser HD 600	300 Ω	91.8 dB/mW	6.6 mW	+20 dB	Comfortable
HiFiMAN Susvara	60 Ω	83.0 dB	50 mW	+15 dB	Comfortable

Noise

Will it hiss?

The manufacturer does not publish an output noise figure for this source, so there is no hiss estimate here. If you have a measured figure, the hiss calculator takes it.

Damping

Output impedance and the one-eighth rule

At 0Ω output impedance this source satisfies the one-eighth rule with every headphone in the database, down to the 3Ω in-ears. Nothing here will have its frequency response shaped by the source.

Check any pair.

Cheaper

The cheapest thing here that does the same job

Source	Type	Price	Into 300 Ω	Output impedance	Output noise
Schiit Magni Heresy	desktop amplifier	$99	410 mW	0.25 Ω	1.5 µV unverified
Schiit Magni Unity	desktop amplifier	$119	415 mW	0.1 Ω	1.59 µV
Topping L30 II	desktop amplifier	$149	560 mW	0.1 Ω	0.3 µV

Of the 280 sources here, 15 do everything the SMSL DO400 does as a headphone output: reach 100 dB on every headphone it reaches and stay inside the one-eighth rule wherever it does. The cheapest of them is the Schiit Magni Heresy at $99, against this one’s $520 — $421 less, and a desktop amplifier rather than a desktop DAC/amp.

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

Alternatives

Compared with its closest rivals: vs FiiO K9 Pro · vs JDS Labs Element III MK2 · vs JDS Labs Element IV.

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

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SMSL DO400: power output and what it will drive

What it actually puts out

Where these numbers come from

Against 40 well-known headphones

Will it hiss?

Output impedance and the one-eighth rule

The cheapest thing here that does the same job

Other desktop DAC/amps at a similar price

JDS Labs Element IV

HiFiMAN EF500

JDS Labs Element III MK2

Topping DX5

xDuoo XA-10

Cambridge Audio DacMagic 200M