FiiO Warmer R2R – 24-bit R2R DAC with E88CC tube buffer

The FiiO Warmer R2R is a high-quality desktop DAC designed for music lovers who want to combine digital precision with a natural and engaging presentation. FiiO combines its proprietary fully differential 24-bit R2R DAC with an analogue buffer stage built around four JJ Electronic E88CC tubes. The result is a DAC focused not only on technical performance, but also on relaxed and involving long-term listening.

With USB-C, coaxial and optical digital inputs, RCA and balanced XLR outputs, selectable NOS and OS modes and high-resolution playback up to 32-bit/384 kHz PCM and DSD256 via USB, the Warmer R2R can be integrated into a wide range of modern hi-fi systems.

True fully differential 24-bit R2R architecture

At the digital heart of the FiiO Warmer R2R is FiiO's proprietary four-way, fully differential R2R architecture. Rather than relying on a conventional delta-sigma DAC chip, the design uses 192 high-precision thin-film resistors with a tolerance of 0.1%.

R2R conversion is appreciated by many demanding listeners for its direct approach to digital-to-analogue conversion and the natural presentation it can provide. The Warmer therefore focuses not merely on analytical sharpness, but on a coherent, fluid and musical listening experience.

Four JJ Electronic E88CC tubes

Following the R2R conversion stage is a classic tube buffer built around four JJ Electronic E88CC tubes manufactured in Slovakia. The tubes operate from an approximately ±28 V supply, and FiiO specifies a potential service life of up to around 10,000 operating hours.

The tube buffer is designed to add subtle body and organic texture to the analogue output without unnecessarily masking detail or transparency. This makes the Warmer R2R particularly appealing in systems that are naturally very neutral or analytical, as well as to listeners who simply appreciate the character of a tube output stage.

NOS and OS playback modes

Selectable NOS and OS modes allow the digital processing to be adapted to personal preference. NOS mode avoids digital oversampling and can provide a more direct and relaxed presentation, while OS mode employs oversampling with a stronger emphasis on precision and definition.

The preferred setting will depend on the recording, the rest of the system and personal taste. The ability to switch easily between both approaches is therefore a valuable feature for critical listeners.

High-resolution USB, coaxial and optical inputs

The FiiO Warmer R2R offers three digital inputs. USB-C supports PCM up to 32-bit/384 kHz and DSD256. The coaxial input supports PCM up to 24-bit/192 kHz, while the optical input supports up to 24-bit/96 kHz.

The USB interface supports both UAC 1.0 and UAC 2.0, allowing compatibility with a broad range of computers, music players, smartphones and compatible game consoles. Bluetooth is not built in, so wireless playback requires an external streamer or digital Bluetooth receiver.

RCA and balanced XLR outputs

On the analogue side, the Warmer offers both conventional stereo RCA and balanced XLR outputs. It can therefore be connected to a wide variety of integrated amplifiers, preamplifiers and other hi-fi components.

Important: the FiiO Warmer R2R does not include a volume control or headphone amplifier. When connecting it directly to a power amplifier or active loudspeakers, safe volume control must therefore be provided elsewhere in the audio chain.

46 W linear power supply with toroidal transformer

FiiO equips the Warmer with an internal 46 W linear power supply using a toroidal transformer. This design provides stable power while helping to minimise electromagnetic interference, which is particularly relevant in a component combining sensitive digital circuitry with an analogue tube stage.

Mechanical VU meters and classic hi-fi styling

Two large mechanical VU meters dominate the front panel. Their warm illumination complements the tube circuitry and gives the Warmer R2R a distinctive retro-inspired hi-fi appearance.

Measuring approximately 223.5 × 213 × 66.8 mm and weighing around 2.865 kg, the Warmer feels like a substantial desktop audio component despite its relatively compact footprint.

Who is the FiiO Warmer R2R for?

The Warmer R2R is primarily aimed at listeners who already own a good amplifier and want a dedicated DAC with a distinctive technical and musical identity. It is an excellent partner for a CD transport, network streamer, computer or other digital audio source.

If you prefer an R2R solution with integrated volume control and headphone amplification, consider the FiiO K11 R2R or the more extensively equipped FiiO K13 R2R DAC/AMP.

Explore the complete range of FiiO products at Hi-Stands.

Technical specifications FiiO Warmer R2R