Audio-Technica ATH-R70X vs HiFiMAN Ananda Nano: which needs more amplifier?

The Audio-Technica ATH-R70X is 470Ω at 98.0 dB/mW; the HiFiMAN Ananda Nano is 14Ω at 94.0 dB (no reference unit printed). This page is only about what they ask of an amplifier — not how they sound, which no specification on either sheet can tell you.

The HiFiMAN Ananda Nano needs 4.0 dB more than the Audio-Technica ATH-R70X to reach the same loudness — 4.0 mW against 1.6 mW.

The numbers that decide it

SpecificationAudio-Technica ATH-R70XHiFiMAN Ananda Nano
Impedance470 Ω14 Ω
Sensitivity98.0 dB/mW94.0 dB
Sensitivity (voltage)101.3 dB/V112.5 dB/V
Power for 100 dB1.6 mW4.0 mW
Voltage for 100 dB0.86 V0.24 V
Current for 100 dB1.8 mA16.9 mA
Highest source impedance
that leaves them alone (one-eighth rule)
58.75 Ω1.75 Ω
Sources that reach 100 dB
out of 280
277280

One caution before reading the rows. HiFiMAN Ananda Nano printed a decibel figure with no reference unit, so this page reads it as per milliwatt. If it is really per volt, that model needs far more than the table says. Why the two readings differ by so much.

Where the two part company

3 of the 280 sources have the power for the HiFiMAN Ananda Nano but not for the Audio-Technica ATH-R70X — Apple USB-C dongle (EU), Steinberg UR22C, Sony NW-A306.

37 sources are low enough in output impedance for the Audio-Technica ATH-R70X under the one-eighth rule but not for the HiFiMAN Ananda Nano (Zoom AMS-22, Audient EVO 4, ART HeadAmp 4 Pro, 34 more).

277 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.

Both pages in full

Each model has a page of its own with the full source list, the hiss estimate and the provenance of every figure above: Audio-Technica ATH-R70X and HiFiMAN Ananda Nano. Each figure on this page is labelled on those pages with where it came from, including the ones Audio-Technica and HiFiMAN never published — what Audio-Technica publishes and what HiFiMAN publishes, both counted.