SMSL H400 MK2 vs Soncoz SGA1

Short answer

More power: the SMSL H400 MK2, with 2.50 W into 32 Ω; the Soncoz SGA1 has 407 mW (balanced: 9.00 W against 407 mW). The SMSL H400 MK2 drives 1 headphone to 100 dB that the Soncoz SGA1 cannot (Symphonium Titan).
Hiss with sensitive IEMs: cannot be compared — the maker of the SMSL H400 MK2 publishes no noise figure.
Price: the SMSL H400 MK2 costs $61 less, and wherever both makers publish a figure the Soncoz SGA1 shows no advantage for the extra money.

Both are desktop amplifiers, $539 against $600.

The SMSL H400 MK2 reaches 100 dB on 567 of the 567 models here, the Soncoz SGA1 on 566.

Side by side

Every published figure, next to each other

Specification	SMSL H400 MK2	Soncoz SGA1
Power into 32Ω	2.5 W	407 mW
Power into 150Ω	527 mW	207 mW
Power into 300Ω	260 mW	210 mW
Power into 600Ω	130 mW	105 mW
Output impedance	<0.1 Ω	0.1 Ω
Output noise	not published	1.8 µV
Price	$539	$600
Headphones it reaches 100 dB on out of 567	567	566

Not published means the maker leaves it out, so that axis cannot be compared.

Balanced output

The 4.4 mm or XLR socket, rated on its own

Balanced	SMSL H400 MK2	Soncoz SGA1
Socket	4.4mm / 4-pin XLR	4-Pin XLR + 4.4mm
Power into 32Ω	9.0 W	407 mW derived
Power into 300Ω	1.1 W	840 mW
Output impedance	<0.1 Ω	0.05 Ω
Output noise	not published	3.6 µV
Headphones it reaches 100 dB on out of 567	567	566

Through the balanced sockets the SMSL H400 MK2 reaches 100 dB on 567 of the 567 models here and the Soncoz SGA1 on 566. Derived figures are worked out from the loads the maker did publish.

How solid these numbers are

Where each power figure comes from

Load	SMSL H400 MK2	Soncoz SGA1
32 Ω	Published	Derived
150 Ω	Derived	Derived
300 Ω	Published	Published
600 Ω	Published	Published

Both makers publish a power rating. SMSL H400 MK2 publishes at 32 Ω, at 300 Ω and at 600 Ω; Soncoz SGA1 at 300 Ω and at 600 Ω. The other rows are worked out from those.

So the two columns are not equally firm row by row: at 32 Ω only the SMSL H400 MK2 figure is the maker’s own. On those rows the derived number is the one to doubt first.

What the labels mean.

What separates them

The headphones that tell them apart

1 headphone reaches 100 dB on the SMSL H400 MK2 but not on the Soncoz SGA1 — Symphonium Titan.

566 of the 567 models here reach 100 dB on both.

On real headphones

Headroom and hiss on 8 models, both sources

Headroom is at a 100 dB SPL peak.

The widest gap on the list is the Campfire Audio Andromeda 2020: SMSL H400 MK2 has +28 dB of headroom there against +15 dB. 14 dB is about 25 times the power, which matters for peaks rather than for how loud the music sits.

The hiss columns are empty for SMSL H400 MK2 because that maker publishes no output noise figure.

Headphone	Impedance	Needs	SMSL H400 MK2 headroom	Soncoz SGA1 headroom	SMSL H400 MK2 hiss	Soncoz SGA1 hiss
Shure SE846	9 Ω	0.04 mW	+48 dB	+35 dB	not published	20 dB
Campfire Audio Andromeda 2020	9 Ω	4.0 mW	+28 dB	+15 dB	not published	-0 dB
Audeze LCD-2 Classic	70 Ω	0.79 mW	+32 dB	+25 dB	not published	-2 dB
Beyerdynamic DT 1990 Pro (250Ω)	250 Ω	0.63 mW	+27 dB	+25 dB	not published	-7 dB
HiFiMAN HE400se	25 Ω	7.9 mW	+26 dB	+16 dB	not published	-8 dB
Audio-Technica ATH-R70X	470 Ω	1.6 mW	+20 dB	+19 dB	not published	-14 dB
Sennheiser HD 600	300 Ω	6.6 mW	+16 dB	+15 dB	not published	-18 dB
HiFiMAN Susvara	60 Ω	50 mW	+14 dB	+8 dB	not published	-20 dB

What the price difference buys

The gap in dollars, against the gap in numbers

The Soncoz SGA1 costs $61 more than the SMSL H400 MK2, and on these three axes the money buys nothing: among the 567 models here there is not one that the Soncoz SGA1 handles and the SMSL H400 MK2 does not — not on power, not on the one-eighth rule, not on hiss. The traffic runs the other way: the cheaper SMSL H400 MK2 drives one model to 100 dB that the Soncoz SGA1 does not.

Only published figures count here; blank axes are counted separately.

Both pages in full

Each in full: SMSL H400 MK2 and Soncoz SGA1.

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