COSMO vs PARA: which needs more amplifier?

The Moondrop COSMO is 15Ω at 81.8 dB/mW; the Moondrop PARA is 8Ω at 80.0 dB/mW. This page covers what they ask of an amplifier, not how they sound.

The PARA needs 1.8 dB more than the COSMO to reach the same loudness — 100 mW against 66 mW.

Side by side

The numbers that decide it

Specification	COSMO	PARA
Impedance	15 Ω	8 Ω
Sensitivity	81.8 dB/mW	80.0 dB/mW
Sensitivity (voltage)	100.0 dB/V	101.0 dB/V
Power for 100 dB	66 mW	100 mW
Voltage for 100 dB	1.00 V	0.89 V
Current for 100 dB	66.4 mA	111.8 mA
Highest source impedance that leaves them alone (one-eighth rule)	1.88 Ω	1.00 Ω
Sources that reach 100 dB out of 280	188	130

What separates them

Where the two part company

58 of the 280 sources have the power for the COSMO but not for the PARA — Tanchjim Stargate II, ddHiFi TC35Air, ddHiFi TC35AL, 55 more.

9 sources are low enough in output impedance for the COSMO under the one-eighth rule but not for the PARA (FiiO KA13, FiiO K11, Schiit Vali 2+, 6 more).

130 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 PARA is more demanding than 100% of the 567 non-electrostatic models in this database; the COSMO than 99%.

dB SPL	COSMO power	COSMO voltage	PARA power	PARA voltage
80	0.66 mW	100 mV	1.0 mW	89 mV
85	2.1 mW	0.18 V	3.2 mW	0.16 V
90	6.6 mW	0.31 V	10 mW	0.28 V
95	21 mW	0.56 V	32 mW	0.50 V
100	66 mW	1.00 V	100 mW	0.89 V
105	209 mW	1.77 V	316 mW	1.59 V

What drives both

The cheapest source that satisfies both

Source	Price	Headroom, COSMO	Headroom, PARA	Output impedance	Noise
FiiO KA11	$29	5.4 dB	0.9 dB	0.7 Ω	1.7 µV
JDS Labs Atom+ (2nd gen)	$99	8.5 dB	4.0 dB	0.7 Ω	1.99 µV
FiiO KA15	$109	6.1 dB	1.6 dB	0.8 Ω	1.7 µV

Of the 280 sources here, 130 reach 100 dB on both. 53 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 53 is the FiiO KA11, at $29. It leaves 5.4 dB of headroom on the COSMO and 0.9 dB on the PARA, its output impedance is 0.7 Ω against a one-eighth limit of 1.88 Ω and 1.00 Ω, and its noise figure puts the hiss floor 35 dB and 34 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
COSMO	13Hz- 58kHz (IEC61094, Free Field)	not printed	IEC61094 (free field)
	20Hz- 20kHz (IEC60318-4, -3dB)	-3 dB	IEC60318-4
PARA	15-53kHz (IEC61094, Free Field)	not printed	IEC61094 (free field)
	20-20kHz (IEC60318-4, -3dB)	-3 dB	IEC60318-4

Moondrop prints two ranges, “13Hz- 58kHz (IEC61094, Free Field)” and “20Hz- 20kHz (IEC60318-4, -3dB)”, for the COSMO and two ranges, “15-53kHz (IEC61094, Free Field)” and “20-20kHz (IEC60318-4, -3dB)”, for the PARA.

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 COSMO and Moondrop PARA. Every figure on this page comes from what Moondrop published, or is derived from it — what that maker publishes, counted.