FiiO JT1: how much amplifier do you need?

The FiiO JT1 is 32Ω with a sensitivity of 88.1 dB/mW, which is 103.0 dB/V. To reach 100 dB SPL — genuinely loud, louder than most people listen — it needs 15 mW, or 0.70 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. 259 of 280 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. Why the unit matters.

FiiO, as the shop reproduces it, publishes this as 103 dB/V (1 Vrms @ 1 kHz) — a figure per volt, not per milliwatt. At 32Ω the two differ by 14.9 dB, so the 88.1 dB/mW above is that published number converted, not a different measurement.

This is the conversion that online calculators skip. Quote the per-volt number as if it were per-milliwatt and this headphone looks 15 dB easier to drive than it is — which is roughly the difference between a dongle being enough and not being enough.

One caveat about the source. Almost everything in this database comes from a document the maker published. This entry does not: the figures above stand on someone else's product page — FiiO's German distributor shop and Apos Audio, a retailer — and not on any page FiiO publishes. Shops usually copy the factory table faithfully and this one may well be exact — but a shop can also carry an old revision, and if FiiO changes the number there is nothing here that would notice. It is the weakest provenance on this site, which is why it is written on the page rather than left in a footnote.

FiiO publishes thorough specifications for most of its catalogue, but the JT1 has been taken off the site: fiio.com/jt1 returns 404 and the headphone index no longer lists it. What is left is a distributor's copy of a table FiiO itself no longer shows.

Source: fiio-shop.de, apos.audio. How this data was built.

Most people listen between 75 and 85 dB; the 100 dB row leaves room for peaks.

The 15 cheapest of the 280 sources here that reach 100 dB SPL into 32Ω with at least 10 dB of headroom and no known hiss or output-impedance problem with these headphones. All 280 sources, judged for these headphones.

Hiss. At 103.0 dB/V these are sensitive enough to reveal a source's own noise floor. The noisiest source in the database, the Schiit Mjolnir 3, would put its hiss at roughly 11 dB SPL in these headphones — clearly audible in quiet passages. Check your own source.

Output impedance. At 32Ω these want a source output impedance below 4.00Ω to satisfy the one-eighth rule; 35 of the 192 sources that publish one miss it. Check yours here.

Compared with its stablemates: vs FT1 · vs FT1 Pro · vs FT3 (32Ω) · vs FT3 (350Ω) · vs FT5.

Compare any two or browse all 578. Every FiiO headphone here.