Armature Art 24 vs SOLIS II: which needs more amplifier?

The Moondrop Armature Art 24 is 5.8Ω at 96.6 dB/mW; the Moondrop SOLIS II is 10Ω at 101.0 dB/mW. This page covers what they ask of an amplifier, not how they sound.

The Armature Art 24 needs 4.4 dB more than the SOLIS II to reach the same loudness — 2.2 mW against 0.79 mW.

Side by side

The numbers that decide it

Specification	Armature Art 24	SOLIS II
Impedance	5.8 Ω	10 Ω
Sensitivity	96.6 dB/mW	101.0 dB/mW
Sensitivity (voltage)	119.0 dB/V	121.0 dB/V
Power for 100 dB	2.2 mW	0.79 mW
Voltage for 100 dB	0.11 V	89 mV
Current for 100 dB	19.4 mA	8.9 mA
Highest source impedance that leaves them alone (one-eighth rule)	0.72 Ω	1.25 Ω
Sources that reach 100 dB out of 280	279	280

What separates them

Where the two part company

1 of the 280 sources has the power for the SOLIS II but not for the Armature Art 24 — Steinberg UR22C.

41 sources are low enough in output impedance for the SOLIS II under the one-eighth rule but not for the Armature Art 24 (FiiO SnowSky Tiny B, FiiO KA15, FiiO BTR15, 38 more).

279 of the 280 sources here reach 100 dB on both.

At the level you actually listen at

What each one needs from 80 to 105 dB

The Armature Art 24 is more demanding than 37% of the 567 non-electrostatic models in this database; the SOLIS II than 28%.

dB SPL	Armature Art 24 power	Armature Art 24 voltage	SOLIS II power	SOLIS II voltage
80	0.02 mW	11 mV	7.9 µW	9 mV
85	0.07 mW	20 mV	0.03 mW	16 mV
90	0.22 mW	36 mV	0.08 mW	28 mV
95	0.69 mW	63 mV	0.25 mW	50 mV
100	2.2 mW	0.11 V	0.79 mW	89 mV
105	6.9 mW	0.20 V	2.5 mW	0.16 V

What drives both

The cheapest source that satisfies both

Source	Price	Headroom, Armature Art 24	Headroom, SOLIS II	Output impedance	Noise
JadeAudio JA11	$20	4.0 dB	10.7 dB	0.5 Ω	1.7 µV
FiiO KA11	$29	16.1 dB	22.9 dB	0.7 Ω	1.7 µV
FiiO BTR11	$36	8.7 dB	15.5 dB	0.5 Ω	8.0 µV

Of the 280 sources here, 279 reach 100 dB on both. 43 of them also publish an output impedance low enough for both under the one-eighth rule and a noise figure that stays below the audible-hiss threshold with both.

The cheapest of the 43 is the JadeAudio JA11, at $20. It leaves 4.0 dB of headroom on the Armature Art 24 and 10.7 dB on the SOLIS II, its output impedance is 0.5 Ω against a one-eighth limit of 0.72 Ω and 1.25 Ω, and its noise figure puts the hiss floor 16 dB and 14 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.

Try any other source.

Frequency response

What each sheet prints, and what it is worth

Model	As printed	Tolerance	Standard
Armature Art 24	7Hz-35kHz	not printed	not printed
	20Hz-20kHz (IEC60318-4, -3dB)	-3 dB	IEC60318-4
SOLIS II	7Hz-40kHz	not printed	not printed
	20Hz-20kHz (IEC60318-4, 3dB)	3 dB	IEC60318-4

Moondrop prints two ranges, “7Hz-35kHz” and “20Hz-20kHz (IEC60318-4, -3dB)”, for the Armature Art 24 and two ranges, “7Hz-40kHz” and “20Hz-20kHz (IEC60318-4, 3dB)”, for the SOLIS II.

Both sheets print a tolerance, which is rare enough to be worth pointing at: only 58 of the 490 models with a printed range do. These two ranges can be set against each other, because each of them says how far down the response is allowed to be at the ends.

Not a measurement; maker by maker.

Both pages in full

Both have a page of their own. In full: Moondrop Armature Art 24 and Moondrop SOLIS II. Every figure on this page comes from what Moondrop published, or is derived from it — what that maker publishes, counted.