Schiit Asgard 3 vs Schiit Valhalla 2

Short answer

More power: the Schiit Asgard 3, with 3.50 W into 32 Ω; the Schiit Valhalla 2 has 115 mW. The Schiit Asgard 3 drives 6 headphones to 100 dB that the Schiit Valhalla 2 cannot (Moondrop COSMO, Moondrop PARA, Symphonium Crimson, 3 more).
Hiss with sensitive IEMs: cannot be compared — the maker of the Schiit Valhalla 2 publishes no noise figure.
Output impedance: 522 headphones are left alone by the Schiit Asgard 3 under the one-eighth rule but coloured by the Schiit Valhalla 2 (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Nio, 519 more).
Price: the Schiit Asgard 3 costs $70 less, and wherever both makers publish a figure the Schiit Valhalla 2 shows no advantage for the extra money.

Both are desktop amplifiers, $279 against $349.

The Schiit Asgard 3 reaches 100 dB on 567 of the 567 models here, the Schiit Valhalla 2 on 561.

Every published figure, next to each other

Specification	Schiit Asgard 3	Schiit Valhalla 2
Power into 32Ω	3.5 W	115 mW
Power into 150Ω	972 mW	426 mW
Power into 300Ω	600 mW	800 mW
Power into 600Ω	300 mW	450 mW
Output impedance	0.2 Ω	14.0 Ω
Output noise	1.5 µV unverified	not published
Price	$279	$349
Headphones it reaches 100 dB on out of 567	567	561

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

Where each power figure comes from

Load	Schiit Asgard 3	Schiit Valhalla 2
32 Ω	Published	Derived
150 Ω	Derived	Derived
300 Ω	Published	Published
600 Ω	Published	Published

Both makers publish a power rating. Schiit Asgard 3 publishes at 32 Ω, at 300 Ω and at 600 Ω; Schiit Valhalla 2 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 Schiit Asgard 3 figure is the maker’s own. On those rows the derived number is the one to doubt first.

What the labels mean.

The headphones that tell them apart

6 headphones reach 100 dB on the Schiit Asgard 3 but not on the Schiit Valhalla 2 — Moondrop COSMO, Moondrop PARA, Symphonium Crimson, 3 more.

522 headphones are left alone by the Schiit Asgard 3 under the one-eighth rule but coloured by the Schiit Valhalla 2 (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Nio, 519 more).

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

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: Schiit Asgard 3 has +28 dB of headroom there against +9 dB. 19 dB is about 87 times the power, which matters for peaks rather than for how loud the music sits.

The hiss columns are empty for Schiit Asgard 3 and Schiit Valhalla 2 because neither maker publishes no output noise figure.

Headphone	Impedance	Needs	Schiit Asgard 3 headroom	Schiit Valhalla 2 headroom	Schiit Asgard 3 hiss	Schiit Valhalla 2 hiss
Shure SE846	9 Ω	0.04 mW	+48 dB	+29 dB damping	not published	not published
Campfire Audio Andromeda 2020	9 Ω	4.0 mW	+28 dB	+9 dB damping	not published	not published
Audeze LCD-2 Classic	70 Ω	0.79 mW	+34 dB	+25 dB damping	not published	not published
Beyerdynamic DT 1990 Pro (250Ω)	250 Ω	0.63 mW	+30 dB	+30 dB	not published	not published
HiFiMAN HE400se	25 Ω	7.9 mW	+27 dB	+11 dB damping	not published	not published
Audio-Technica ATH-R70X	470 Ω	1.6 mW	+24 dB	+25 dB	not published	not published
Sennheiser HD 600	300 Ω	6.6 mW	+20 dB	+21 dB	not published	not published
HiFiMAN Susvara	60 Ω	50 mW	+16 dB	+6 dB damping	not published	not published

The gap in dollars, against the gap in numbers

The Schiit Valhalla 2 costs $70 more than the Schiit Asgard 3, and on these three axes the money buys nothing: among the 567 models here there is not one that the Schiit Valhalla 2 handles and the Schiit Asgard 3 does not — not on power, not on the one-eighth rule, not on hiss. The traffic runs the other way: the cheaper Schiit Asgard 3 drives 6 models to 100 dB and leaves 522 alone under the one-eighth rule that the Schiit Valhalla 2 does not.

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