FD5

Tonal Profile

A single 12 mm beryllium-coated DLC dynamic — one driver, no crossover, and 32 Ω that behaves like 32 Ω across the band. FiiO also publishes max input power (100 mW), which puts the voltage limit near 1.8 Vrms.

Gain Staging Advice

109 dB/mW at 32 Ω is about 124 dB/V — moderate for an in-ear, high for anything else. The swappable 4.4 mm plug doubles the available voltage on a balanced source, which this earphone does not need; use it for the lower output impedance if the amplifier has it, not for the power.