FIIO K13 Compact Desktop R2R architecture DAC and Headphone Amplifier

The FiiO K13 R2R is a desktop DAC, headphone amplifier and preamp built around FiiO’s own fully differential 24-bit R2R resistor-array DAC, for a uniquely rich and musical sound. Its fully balanced circuit delivers 2,400mW per channel from the 4.4mm output, XLR and RCA outputs feed active speakers or a power amplifier, and USB, coaxial, optical and LDAC Bluetooth inputs, a 10-band PEQ, a remote and AC or DC power make it a complete desktop hub. It won Headfonics’ Writer’s Choice 2025 (Bang for Buck) and an “Outstanding” rating from A British Audiophile.

A fully differential 24-bit R2R DAC

FiiO’s proprietary four-channel, fully differential R2R DAC uses 48 precision thin-film resistors per channel, 192 in all, each with 0.1% accuracy and low (30ppm) temperature drift. An FPGA feeds the four ladders. Compared with a typical architecture, the fully differential design gives lower noise and fewer FFT harmonics, for a darker musical background.

NOS and OS modes

NOS (non-oversampling) mode decodes at the original sample rate for an authentic, organic and captivating sound; OS (oversampling) mode upsamples everything to 384kHz for an even more refined, clear sound. DSD is decoded natively as 1-bit (it plays slightly quieter, which is normal). As FiiO says, which you prefer is personal.

A fully balanced amplifier

The whole chain, from the R2R DAC and low-pass filter to the volume control and the OPA1642 and TPA6120A headphone amplifier, is fully differential, for strong interference rejection, minimal distortion and wide dynamic range, with gain control, headphone protection and pop elimination. It delivers 2,400mW + 2,400mW into 32Ω balanced (600mW into 300Ω) and 1,220mW from the 6.35mm output, enough to bring out every detail from both sensitive IEMs and full-size headphones.

Three gains, three volume curves

Each of the three gain levels has its own volume curve, so the K13 R2R adapts to all kinds of IEMs and headphones, and the headphone and preamp volumes are remembered separately.

A specially designed power supply

The built-in 30W switching supply sits under a nickel-plated alloy shield for better interference resistance and cleaner power. A multi-rail design with up to 18 low-noise LDOs and five DC-DC converters gives strong, clean power, and ELNA RA3 silk-film audio capacitors and audio tantalum capacitors keep it pure and stable for a warm, natural sound. An external DC input (12V, 2.5A or more, 5.5 × 2.1mm) lets you add a high-performance linear supply for a different sound.

Preamp, DAC and Bluetooth hub

With inputs for USB (PCM 384kHz/32-bit, DSD256 and MQA), coaxial and optical (192kHz/24-bit) and Bluetooth 5.4 (LDAC, AAC and SBC), and XLR and RCA outputs, the K13 R2R works as a preamplifier for active speakers or a power amplifier as well as a headphone amp.

A 10-band PEQ

The XMOS XU316 platform runs a 10-band PEQ in every mode: use presets such as “Retro PEQ”, simulate or correct your headphones’ response, auto-EQ, and export, import, share and save curves in the FiiO Control app, or in the web version at fiiocontrol.fiio.com when using USB (PEQ works up to 192kHz/24-bit).

Display, skylight and controls

A custom high-contrast LCD shows the sample rate, volume, gain and output mode, and can stay on without burn-in. The thick unibody aluminium case continues the K11 series’ minimalist style, with a new “skylight” window onto the R2R resistors and flowing, customisable RGB lighting that shows the sample rate. Control it with two knobs, the infrared remote or the FiiO Control app; overheating and overload protection and a 1–99 minute sleep timer add peace of mind.

Good to know

• For an external linear supply, the FiiO PL50 gives 12V on a 5.5 × 2.1mm plug.
• The smaller K11 R2R uses a similar R2R design.
• In the box: K13 R2R, infrared remote, AC power cord, USB cable, headphone adapter, quick start guide and warranty card. Black or silver.