Audio-Technica ATH-R70xa: how much amplifier do you need?

The Audio-Technica ATH-R70xa is 470Ω with a sensitivity of 97.0 dB/mW, which is 100.3 dB/V. To reach 100 dB SPL — genuinely loud, louder than most people listen — it needs 2.0 mW, or 0.97 V across the drivers.

That is a moderate load. Most USB dongles handle it without complaint; the weakest phone outputs will run out of volume before they run out of quality. 148 of 156 sources here have enough headroom. The cheapest portable source that does the job is the Generic CX31993 dongles at $12.

Sensitivity here is in dB per milliwatt. Manufacturers often quote dB per volt instead and leave the unit off, which is the single most common reason online calculators give answers that are 10–15 dB wrong. The converter explains the difference.

Audio-Technica publishes this directly as 97 dB/mW (1 mW (implied by the /mW unit; no frequency stated)), per milliwatt, so nothing was converted.

Source: audio-technica.com. How this data was built.

Most people listen between 75 and 85 dB. The 100 dB row is the one worth planning around: it gives you headroom for dynamic peaks without designing your system for a volume that would damage your hearing in under fifteen minutes. The safe listening calculator puts numbers on that.

Every source in the database, judged at 100 dB SPL into 470Ω. “Headroom” is how much power is left over above what the headphone needs — 10 dB means ten times the required power, which is what you want for dynamic peaks.

Hiss. At 100.3 dB/V these are sensitive enough to reveal a source's own noise floor. The noisiest source in the database, the Schiit Vali 2+, would put its hiss at roughly 8 dB SPL in these headphones — faintly audible in a silent room. The hiss calculator lets you check your own amplifier's noise figure.

Output impedance. At 470Ω these want a source output impedance below 58.75Ω to satisfy the one-eighth rule. 1 of the 156 sources here miss it, the worst being the Bottlehead Crack (OTL kit) at 120.0Ω. Above that threshold the source starts shaping the frequency response. Check yours here.

Or open the comparison tool to put any two models side by side, or browse all 402.