COSMO vs PARA 2: which needs more amplifier?

The Moondrop COSMO is 15Ω at 81.8 dB/mW; the Moondrop PARA 2 is 9Ω at 85.5 dB/mW. This page covers what they ask of an amplifier, not how they sound.

The COSMO needs 3.7 dB more than the PARA 2 to reach the same loudness — 66 mW against 28 mW.

The numbers that decide it

SpecificationCOSMOPARA 2
Impedance15 Ω9 Ω
Sensitivity81.8 dB/mW85.5 dB/mW
Sensitivity (voltage)100.0 dB/V106.0 dB/V
Power for 100 dB66 mW28 mW
Voltage for 100 dB1.00 V0.50 V
Current for 100 dB66.4 mA56.0 mA
Highest source impedance
that leaves them alone (one-eighth rule)
1.88 Ω1.12 Ω
Sources that reach 100 dB
out of 280
188223

Where the two part company

35 of the 280 sources have the power for the PARA 2 but not for the COSMO — FiiO SnowSky Tiny B, Fosi Audio N3, Truthear SHIO, 32 more.

8 sources are low enough in output impedance for the COSMO under the one-eighth rule but not for the PARA 2 (FiiO KA13, FiiO K11, Schiit Vali 2+, 5 more).

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

What each one needs from 80 to 105 dB

The COSMO is more demanding than 99% of the 567 non-electrostatic models in this database; the PARA 2 than 89%.

dB SPLCOSMO powerCOSMO voltagePARA 2 powerPARA 2 voltage
800.66 mW100 mV0.28 mW50 mV
852.1 mW0.18 V0.89 mW90 mV
906.6 mW0.31 V2.8 mW0.16 V
9521 mW0.56 V8.9 mW0.28 V
10066 mW1.00 V28 mW0.50 V
105209 mW1.77 V89 mW0.90 V

The cheapest source that satisfies both

SourcePriceHeadroom, COSMOHeadroom, PARA 2Output impedanceNoise
FiiO KA11$295.4 dB6.9 dB0.7 Ω1.7 µV
FiiO BTR13$592.3 dB3.8 dB0.6 Ω1.0 µV
FiiO KA3$792.3 dB3.8 dB0.5 Ω1.7 µV

Of the 280 sources here, 188 reach 100 dB on both. 60 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 60 is the FiiO KA11, at $29. It leaves 5.4 dB of headroom on the COSMO and 6.9 dB on the PARA 2, its output impedance is 0.7 Ω against a one-eighth limit of 1.88 Ω and 1.12 Ω, and its noise figure puts the hiss floor 35 dB and 29 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.

Try any other source.

What each sheet prints, and what it is worth

ModelAs printedToleranceStandard
COSMO13Hz- 58kHz (IEC61094, Free Field)not printedIEC61094 (free field)
 20Hz- 20kHz (IEC60318-4, -3dB)-3 dBIEC60318-4
PARA 220Hz-42kHz (IEC61094, Free Field)not printedIEC61094 (free field)
 20Hz-20kz (IEC60318-4, -3dB)-3 dBIEC60318-4

Moondrop prints two ranges, “13Hz- 58kHz (IEC61094, Free Field)” and “20Hz- 20kHz (IEC60318-4, -3dB)”, for the COSMO and two ranges, “20Hz-42kHz (IEC61094, Free Field)” and “20Hz-20kz (IEC60318-4, -3dB)”, for the PARA 2.

PARA 2: Moondrop prints the narrow range as “20Hz-20kz”, without the H. It is quoted here exactly as it stands on the page.

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

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