FiiO WARMER - Desktop R2R Tube Buffer and DAC

The FiiO WARMER R2R is a desktop DAC that pairs FiiO’s own 24-bit R2R resistor-ladder DAC with a tube buffer of four JJ Electronic E88CC valves, to give your music an invitingly warm, rich tube sound. Two big backlit mechanical VU meters swing with the music, a 46W toroidal linear power supply keeps it clean, and USB, coaxial and optical inputs feed RCA and XLR balanced outputs for your amplifier, active speakers or headphone amp. It won a CIHE EHA 2025 Technology Innovation Award and an Editor’s Choice from Poland’s Audio Video magazine, and is Hi-Res Audio certified.

Go for a bolder flavour

The WARMER takes its inspiration from the legacy of the timeless Hong Kong band the Wynners, and as its name suggests, it aims to infuse music with a warm, beautiful tube sound. From the sway of the warm-hued VU meters to the pairing of an R2R DAC with vacuum tubes, you can sense the warmth of the music every time you listen.

FiiO’s own fully differential R2R DAC

The star of the show is FiiO’s proprietary four-way, fully differential, true 24-bit R2R DAC: 192 high-precision thin-film resistors (48 in each of the four arrays) with 0.1% accuracy and an ultra-low drift of 30ppm. It gives the WARMER its distinctly captivating sound. An FPGA turns the incoming serial data into parallel data for the four resistor arrays; DSD is converted to PCM first.

NOS or OS: two flavours

A switch on the back chooses the mode. NOS (non-oversampling) decodes at the original sample rate, for the allure of pure, original audio. OS (oversampling) upsamples everything to 384kHz, for better audio performance and a more detailed, clearer sound.

Four JJ Electronic E88CC tubes

The tube buffer stage uses four brand-new JJ Electronic E88CC valves from Slovakia, run from a ±28V supply and rated for a long 10,000-hour life. FiiO optimised the core circuit of the classic tube buffer preamplifier to impart a sweet, organic tube flavour, with real richness and fullness. JJ Electronic, founded in 1993, is a renowned maker of vacuum tubes, capacitors and amplifiers, widely used in guitar and hi-fi amplifiers, recording studios and audiophile equipment.

Extra-large backlit VU meters

The two retro, warm-hued, LED-backlit VU meters are true mechanical meters, driven by a dedicated chip. As the music plays, the needles move in time with it: don’t just listen to your music, see and feel it.

46W linear power supply

A 46W low-noise, low-ripple toroidal audio transformer powers the WARMER. Its core, wound from non-oriented silicon steel strip, is efficient with low eddy-current losses, and its corner-free windings give a more uniform magnetic field with less leakage, so the circuits are fed clean power for a pristine sound.

Connections

Connect a computer, phone, digital music player, CD player and more by USB-C, coaxial or optical, and choose the input with the knob on the front. The RCA and XLR balanced line outputs work at the same time, at a fixed level, to feed speakers, amplifiers or headphone amplifiers. A rear switch selects UAC 2.0 or driver-free UAC 1.0, for games consoles such as the Nintendo Switch and PS5.

Minimalist vintage look

Like FiiO’s K-series desktop units, the WARMER has a classic square-and-round design that blends vintage charm with minimalism. The grille lets heat escape quickly, so it keeps delivering high-quality sound for years. Choose black or silver.

Systems FiiO suggests

• Headphone system: a source such as the FiiO M21, the WARMER, a FiiO K15 as the headphone amp, and FT13 headphones.
• CD system: the FiiO DP11 CD player into the WARMER, then a headphone amplifier and FT15 headphones.
• TV system: your TV’s digital output into the WARMER and on to FiiO SP5 active speakers.

Good to know

• The WARMER has no headphone output and no volume control: connect it to an amplifier, active speakers or a headphone amp. It isn’t controlled by the FiiO Control app.
• The VU needles may sit up to ±1mm off zero, and the left and right needles may rest slightly apart; FiiO says this is within tolerance and doesn’t affect use.
• Newer batches have upgraded feet pads; FiiO confirms the circuitry and performance are unchanged.
• In the box: WARMER R2R, mains cable, USB cable, spare fuse, quick start guide and warranty card.