Singxer SA-1 vs SMSL SH-X

Short answer

Power: about the same. The Singxer SA-1 has 5.50 W into 32 Ω, the SMSL SH-X 5.50 W. Both drive 567 of the 567 non-electrostatic headphones here to 100 dB, so on that test the difference changes nothing.
Hiss with sensitive IEMs: cannot be compared — the maker of the SMSL SH-X publishes no noise figure.
Output impedance: 51 headphones are left alone by the SMSL SH-X under the one-eighth rule but coloured by the Singxer SA-1 (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Nio, 48 more).
Price: the same, $699.

Both are desktop amplifiers, both at $699.

On raw power they are level: each reaches 100 dB on 567 of the 567 non-electrostatic models here.

Side by side

Every published figure, next to each other

Specification	Singxer SA-1	SMSL SH-X
Power into 32Ω	5.5 W	5.5 W
Power into 150Ω	1.6 W	1.2 W
Power into 300Ω	785 mW	600 mW
Power into 600Ω	380 mW	300 mW
Output impedance	1.4 Ω	<0.1 Ω
Output noise	0.3 µV	not published
Price	$699	$699
Headphones it reaches 100 dB on out of 567	567	567

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

How solid these numbers are

Where each power figure comes from

Load	Singxer SA-1	SMSL SH-X
32 Ω	Published	Published
150 Ω	Derived	Derived
300 Ω	Derived	Published
600 Ω	Published	Published

Both makers publish a power rating. Singxer SA-1 publishes at 32 Ω and at 600 Ω; SMSL SH-X at 32 Ω, 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 300 Ω only the SMSL SH-X 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

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.

51 headphones are left alone by the SMSL SH-X under the one-eighth rule but coloured by the Singxer SA-1 (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Nio, 48 more).

567 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 Beyerdynamic DT 1990 Pro (250Ω): Singxer SA-1 has +32 dB of headroom there against +31 dB. 1 dB is about 1.3 times the power, which matters for peaks rather than for how loud the music sits.

The hiss columns are empty for SMSL SH-X because that maker publishes no output noise figure.

Headphone	Impedance	Needs	Singxer SA-1 headroom	SMSL SH-X headroom	Singxer SA-1 hiss	SMSL SH-X hiss
Shure SE846	9 Ω	0.04 mW	+52 dB damping	+52 dB	4 dB	not published
Campfire Audio Andromeda 2020	9 Ω	4.0 mW	+32 dB damping	+32 dB	-16 dB	not published
Audeze LCD-2 Classic	70 Ω	0.79 mW	+36 dB	+35 dB	-18 dB	not published
Beyerdynamic DT 1990 Pro (250Ω)	250 Ω	0.63 mW	+32 dB	+31 dB	-22 dB	not published
HiFiMAN HE400se	25 Ω	7.9 mW	+29 dB	+30 dB	-23 dB	not published
Audio-Technica ATH-R70X	470 Ω	1.6 mW	+25 dB	+24 dB	-29 dB	not published
Sennheiser HD 600	300 Ω	6.6 mW	+21 dB	+20 dB	-33 dB	not published
HiFiMAN Susvara	60 Ω	50 mW	+18 dB	+18 dB	-35 dB	not published

What the price difference buys

The gap in dollars, against the gap in numbers

These two cost the same, $699, so price settles nothing. Out of the 567 models here, the SMSL SH-X leaves 51 models alone under the one-eighth rule — and on the other side there is no such advantage at all.

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

Each in full: Singxer SA-1 and SMSL SH-X.