ЦАПы — Boulder 812

The 812 is a converter, line preamp and headphone amplifier in a single chassis from Boulder Amplifiers of Colorado. Boulder says it applies the design approach of the 866 integrated amplifier and more than 35 years of work on converters, preamps and amplifier circuits, and it can be used as a preamp, a DAC, a headphone amp or any mix of the three. The company calls it perhaps the highest value product it has ever made. The US price is USD 9,250, and in Europe it sells for EUR 11,900.

Key specs that matter

On the back are two balanced XLR analogue inputs, one XLR preamp output, two Toslink optical inputs, a coaxial digital input, USB-B for a computer, four USB-A ports and Ethernet. The analogue inputs accept up to 6.0 Vrms at 100 kohm balanced, and the output reaches 14.0 Vrms from a 100 ohm balanced source impedance, with a maximum voltage gain of 19.4 dB. THD+N is 0.0017% (-95.5 dB) at 2 V output and 2 kHz, and the clip-to-noise ratio is 116 dB. Frequency response is within +0.00/-0.03 dB from 20 Hz to 5 kHz and reaches -3 dB at 0.02 Hz and 250 kHz. The chassis measures 305 x 305 x 89 mm, weighs 6.35 kg, runs on 90-240 V mains and draws at most 50 W.

Engineering and use context

Its digital circuitry borrows the DSP filtering and converter design of the 866. Streaming is built in as a Roon endpoint, with UPnP playback and AirPlay, and format support covers PCM to 256 kHz, DSD512 and MQA. Level is set by an optically encoded volume control with a 100 dB range in 1.0 dB steps. The front headphone bay offers four connectors - 3.5 mm mini jack, 6.35 mm jack, 4-pin balanced XLR and Pentaconn - and an output exchange button switches the signal between the headphone section and the preamp output. A cover closes the bay against dust when no headphones are connected. The volume knob and the chassis are machined in house, and assembly and quality checks are done at Boulder's own facility. Setup, source labels and headphone sensitivity are handled in the Boulder Controller app, and an RF remote for volume and input selection is optional.

Pairing

The headphone stage delivers 200 mW into 32 ohm and into 150 ohm, and 80 mW into 600 ohm, with THD between 0.0010% and 0.0053% from 2 to 20 kHz, so it drives both low and high impedance headphones. As a preamp, its single XLR output needs a power amplifier fitted with balanced inputs, such as Boulder's own stereo and mono models.

Alternatives

No other Boulder converter is listed among the DACs, which leaves the 812 without a sibling in its category.