ЦАПы — FiiO Warmer R2R

The Warmer R2R is a desktop DAC from FiiO that combines a ladder of discrete resistors designed in-house with a vacuum tube buffer stage and a linear power supply. Black and silver versions are offered, and the front panel carries two mechanical VU meters with LED backlighting driven by a dedicated IC.

Key specs that matter

Conversion uses a proprietary fully differential true 24 bit R2R design in a four-way layout, using 192 high-precision thin-film resistors, 48 per channel, with 0.1% accuracy and 30 ppm temperature drift. The USB input takes PCM up to 384 kHz and 32 bit plus DSD256, the coaxial input 192 kHz and 24 bit, and the optical input 96 kHz and 24 bit. The XLR outputs deliver 3.3 Vrms with an SNR of at least 114 dB A-weighted and THD+N of about 0.053%, while the RCA outputs deliver 1.8 Vrms with at least 112 dB SNR and about 0.052% THD+N. Across 20 Hz to 20 kHz roll-off stays below 0.6 dB on RCA and below 1.5 dB on XLR. The chassis measures 223.5 x 213 x 66.8 mm with feet and weighs about 2865 g.

Engineering and use context

Four JJ Electronic E88CC tubes made in Slovakia work together with two OPA1642 op-amps in the analogue stage. The tube circuit runs from plus and minus 28 V rails, and FiiO rates each tube for 10,000 hours of service. Power comes from a 46 W low-noise, low-ripple linear supply built on a toroidal transformer with a non-oriented silicon steel core, set for either 220-240 V or 100-120 V mains. A GD32F303RET6 microcontroller manages the unit and an SA9312L chip handles USB. Two decoding modes are offered - NOS keeps the file's native sample rate, and OS upsamples all material to the highest rate the DAC supports. A lever switches between UAC1.0 and UAC2.0, so the DAC also works with game consoles and mobile devices that lack UAC2.0 drivers. The classic square casing with rounded edges uses a grille on top to release heat from the tubes.

Pairing

The Warmer R2R has no headphone output, so it feeds an integrated amplifier, a preamplifier, powered speakers or a separate headphone amplifier. Both RCA sets and both XLR sets can run at the same time, which allows one output to go to a speaker system and the other to a headphone amplifier. Digital sources include a computer over USB Type-C, a CD transport over coaxial and a TV over optical.

Alternatives

The FiiO K11 R2R uses the same resistor ladder design in a compact chassis with a built-in headphone amplifier.