DACs — Gustard R30

The R30 is a network streaming DAC and preamplifier from Gustard, built around a fully discrete R2R resistor ladder in place of a bought-in converter IC. It succeeds the R26, Two chassis colours, black and silver, are available at a Gustard list price of USD 3,599.99.

Key specs that matter

Conversion uses a 27 bit complementary R2R ladder network in a quad mono layout, keeping the signal fully balanced from input to output. Signal-to-noise ratio exceeds 121 dB, dynamic range exceeds 123 dB, and THD+N is quoted at 0.00145 percent or lower at 1 kHz. Crosstalk is -139 dB at 10 kHz and intermodulation distortion about 0.002 percent at -1 dBFS. Output level at fixed volume is 2.5 V RMS on RCA and 5.1 V RMS on XLR, with an output impedance of 100 ohm and response flat within 0.2 dB from 20 Hz to 20 kHz. The chassis measures 430 x 300 x 80 mm including feet, and the XLR sockets follow the US pin standard with pin 2 hot.

Engineering and use context

A proprietary Gustard FPGA manages timing, with an SC-cut OCXO oven-controlled oscillator and a GCLK-02 clock module, and a 50 ohm BNC input accepts an external clock. DSD is decoded natively as a 1 bit signal in hardware without conversion to PCM, and filter choices include a non-oversampling mode. Gustard describes the ladder as a self-designed discrete module, and each of the four modules handles one polarity of one channel in the balanced layout. Through the I2S inputs the R30 handles PCM up to 32 bit and 1536 kHz and DSD1024, while USB via an XMOS XU216 interface and the network input reach DSD512. Digital inputs cover USB-B, Ethernet, coaxial, AES/EBU, optical, a microSD card slot and two HDMI I2S ports, one for Gustard sources and one with menu options for third-party devices. Firmware is loaded through a separate USB-C socket. The CelWare streaming board supports Roon, AirPlay, Spotify Connect, HQPlayer NAA and UPnP. The analogue section uses a discrete class A output stage without op-amps, and two toroidal transformers power the digital and analogue circuits separately, with consumption below 35 W.

Pairing

A relay-switched R2R volume control, which can be bypassed, lets the R30 connect over its balanced XLR outputs straight to a power amplifier or active loudspeakers with no separate preamplifier. With volume fixed it works as a source for an integrated amplifier, and touch keys, a display and a remote handle control.

Alternatives

Gustard's earlier R26 remains the brand's other R2R converter below the R30 in its DAC range.