FiiO Darkside Pro Low-noise regulated linear power supply

The FiiO DARKSIDE PRO is a low-noise regulated linear power supply from FiiO’s DARKSIDE power purification series, made to give your hi-fi system an ultra-silent, pitch-black background so the music shines through. It replaces the switch-mode adapter of many FiiO desktop DACs, amplifiers and players with a clean 12V or 15V at up to 3A, from an audiophile-grade 75W toroidal transformer and a fully discrete regulator, with output noise as low as 17µV.

An audiophile-grade 75W toroidal transformer

Designed specifically for low-noise audio, the toroidal transformer uses a grain-oriented silicon steel core for higher efficiency and lower eddy currents, and a seamless, fold-free winding for a uniform magnetic field and minimal magnetic leakage. With 75W in reserve, it handles highly dynamic transients with ease, for solid bass extension and a vivid, clear soundstage.

A fully discrete NMOS regulator

Two high-current IRFZ34N MOSFETs work in parallel to lower internal resistance, improving dynamic range and preserving every nuance of the music. With a fully discrete regulator circuit and a high-precision LT431 reference, the DARKSIDE PRO achieves ultra-low noise (17µV at 12V and 30µV at 15V, A-weighted) and a lightning-fast transient response, while keeping heat down. A relay switches the transformer’s output to match the 12V or 15V setting precisely, which maximises efficiency and greatly reduces heat.

Audiophile-grade components

A Japanese Shindengen D15XB60 bridge rectifier runs cool and stable, reducing micro-interference from current fluctuations. Five ELNA and seven Rubycon filter capacitors and two WIMA film capacitors filter out power-supply noise, and the DC cable uses monocrystalline silver-plated copper to cut transmission loss and shield against electromagnetic interference.

Precise and protected

A three-LED display shows the output voltage, and a precision potentiometer on the back lets you fine-tune it (by ±0.2V) with a small flat-head tool if the reading drifts. A self-resetting fuse protects against overcurrent, and a 1A/250V input fuse protects the mains side.

A minimalist aluminium chassis

The heavy unibody aluminium case shares the minimalist design of FiiO’s K13 series. Its weight and metal construction suppress resonance and block electromagnetic interference, cooling grilles keep it running cool, and it stacks neatly with other FiiO desktop units for a tidy, unified system.

Which devices it powers

FiiO lists the FiiO K11, K11 R2R, K13 R2R, K15, K19, R9, R7, TT13, the K5 Pro and K7 series and Q7, and FiiO portable players powered through USB-C, using a DC to USB-C adapter made for the DARKSIDE PRO (sold separately). Always set the 12V/15V switch to suit your device before connecting it.

Good to know

• The 12V/15V switch must match the voltage your device needs; check its manual or rating label first.
• Before connecting to the mains, check that the input voltage on the label matches your supply.
• For a smaller supply, see FiiO’s PL50.
• In the box: DARKSIDE PRO, DC power cable, AC power cable, spare fuse, quick start guide and warranty card.