JDS Labs Atom Amp 2 vs Little Dot MK II

Short answer

More power: the JDS Labs Atom Amp 2, with 2.65 W into 32 Ω; the Little Dot MK II has 100 mW. The JDS Labs Atom Amp 2 drives 7 headphones to 100 dB that the Little Dot MK II cannot (Moondrop COSMO, Moondrop PARA, Moondrop PARA 2, 4 more).
Hiss with sensitive IEMs: cannot be compared — the maker of the Little Dot MK II publishes no noise figure.
Price: the JDS Labs Atom Amp 2 costs $47 less, and wherever both makers publish a figure the Little Dot MK II shows no advantage for the extra money.

Both are desktop amplifiers, $129 against $176.

The JDS Labs Atom Amp 2 reaches 100 dB on 567 of the 567 models here, the Little Dot MK II on 560.

Side by side

Every published figure, next to each other

Specification	JDS Labs Atom Amp 2	Little Dot MK II
Power into 32Ω	2.6 W	100 mW
Power into 150Ω	567 mW	214 mW
Power into 300Ω	284 mW	300 mW
Power into 600Ω	143 mW	150 mW
Output impedance	0.7 Ω	not published
Output noise	1.33 µV	not published
Price	$129	$176
Headphones it reaches 100 dB on out of 567	567	560

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	JDS Labs Atom Amp 2	Little Dot MK II
32 Ω	Published	Published
150 Ω	Derived	Derived
300 Ω	Derived	Published
600 Ω	Published	Derived

Both makers publish a power rating. JDS Labs Atom Amp 2 publishes at 32 Ω and at 600 Ω; Little Dot MK II at 32 Ω and at 300 Ω. The other rows are worked out from those.

So the two columns are not equally firm row by row: at 600 Ω only the JDS Labs Atom Amp 2 figure is the maker’s own and at 300 Ω only the Little Dot MK II 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

7 headphones reach 100 dB on the JDS Labs Atom Amp 2 but not on the Little Dot MK II — Moondrop COSMO, Moondrop PARA, Moondrop PARA 2, 4 more.

560 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 HiFiMAN HE400se: JDS Labs Atom Amp 2 has +24 dB of headroom there against +10 dB. 14 dB is about 26 times the power, which matters for peaks rather than for how loud the music sits.

The hiss columns are empty for Little Dot MK II because that maker publishes no output noise figure.

Headphone	Impedance	Needs	JDS Labs Atom Amp 2 headroom	Little Dot MK II headroom	JDS Labs Atom Amp 2 hiss	Little Dot MK II hiss
Shure SE846	9 Ω	0.04 mW	+43 dB	+28 dB	17 dB	not published
Campfire Audio Andromeda 2020	9 Ω	4.0 mW	+23 dB	+8 dB	-3 dB	not published
Audeze LCD-2 Classic	70 Ω	0.79 mW	+32 dB	+22 dB	-5 dB	not published
Beyerdynamic DT 1990 Pro (250Ω)	250 Ω	0.63 mW	+27 dB	+26 dB	-10 dB	not published
HiFiMAN HE400se	25 Ω	7.9 mW	+24 dB	+10 dB	-11 dB	not published
Audio-Technica ATH-R70X	470 Ω	1.6 mW	+21 dB	+21 dB	-16 dB	not published
Sennheiser HD 600	300 Ω	6.6 mW	+16 dB	+17 dB	-20 dB	not published
HiFiMAN Susvara	60 Ω	50 mW	+15 dB	+4 dB	-22 dB	not published

What the price difference buys

The gap in dollars, against the gap in numbers

The Little Dot MK II costs $47 more than the JDS Labs Atom Amp 2, and on these three axes the money buys nothing: among the 567 models here there is not one that the Little Dot MK II handles and the JDS Labs Atom Amp 2 does not — not on power, not on the one-eighth rule, not on hiss. The traffic runs the other way: the cheaper JDS Labs Atom Amp 2 drives 7 models to 100 dB that the Little Dot MK II does not.

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

Each in full: JDS Labs Atom Amp 2 and Little Dot MK II.