Moondrop Variations vs Truthear Zero:RED: which needs more amplifier?

The Moondrop Variations is 15.2Ω at 99.8 dB/mW; the Truthear Zero:RED is 17.5Ω at 99.9 dB/mW. This page is only about what they ask of an amplifier — not how they sound, which no specification on either sheet can tell you.

In amplifier terms these two are the same headphone. The gap between what they need for 100 dB is under half a decibel, which is smaller than the step between two clicks of most volume controls.

Every source in the database that drives one of them drives the other. On power, the choice between these two changes nothing about what amplifier you need.

3 sources are low enough in output impedance for the Truthear Zero:RED under the one-eighth rule but not for the Moondrop Variations (Astell&Kern HC3, RME Fireface UFX II, RME Fireface UFX III).

280 of the 280 sources here reach 100 dB on both. That count is about power only — the output-impedance and hiss lines above are separate questions, and a source can pass this one and fail those.

The gap between these two in decibels does not change with volume — it is a property of the two headphones. What changes is the size of the numbers, and it changes fast: every 10 dB costs ten times the power. The row that matters is the one nearest the level you listen at, and for most people that is nearer the top of this table than the bottom.

The Truthear Zero:RED is more demanding than 43% of the 567 non-electrostatic models in this database; the Moondrop Variations than 40%. Both figures use the same measure as the rest of the site: whichever runs out first against a 2 V, 100 mW dongle, voltage or power.

105 dB is included because forum power figures are usually quoted there or higher. It is also a level that damages hearing in minutes — how many minutes is its own calculator.

Of the 280 sources here, 280 reach 100 dB on both. That is the easy axis. 69 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 rest either fail one of those or never printed the number at all, and 208 of them are in the second group.

The cheapest of the 69 is the JadeAudio JA11, at $20. It leaves 11.3 dB of headroom on the Moondrop Variations and 12.1 dB on the Truthear Zero:RED, its output impedance is 0.5 Ω against a one-eighth limit of 1.90 Ω and 2.19 Ω, and its noise figure puts the hiss floor 17 dB and 18 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.

Cheapest that satisfies three published numbers is not the same as best, and none of it is about how either headphone sounds. To put either model against a source this page does not mention, or to change the target loudness, use the amplifier matcher.

Each model has a page of its own with the full source list, the hiss estimate and the provenance of every figure above: Moondrop Variations and Truthear Zero:RED. Every figure on this page comes from what Moondrop and Truthear published, or is derived from it — what Moondrop publishes and what Truthear publishes, both counted.