Pro-Ject Pre Box RS Digital Stereo Preamplifier Digital

"Remarkably Adaptable Sonic Character"

The Pro-Ject Pre Box RS Digital is a future-proof high-end preamplifier, DAC, and headphone amplifier – all in a compact aluminum box that fits easily on desktop or shelf. It includes all of the innovative features of the Pro-Ject DAC Box RS along with a very linear preamplifier with selectable solid-state and tube output stages.

As in all of Pro-Ject's top-class digital products, the Pre Box RS Digital uses state-of-the-art PCM1792 DAC chips from Texas Instruments. But with this component, Pro-Ject uses not one, but two of these DACs in a dual differential mode to achieve ultimate fidelity. But that's not all. As a selectable feature, you can choose to employ a second DAC chip from Texas Instruments for 32-bit/384 kHz processing.

The Pro-Ject Pre Box RS Digital won an "Outstanding" rating from German's Stereoplay magazine. The June 2014 review called it "extremely compact, and for its size an almost sensationally equipped DAC-preamp. It has a remarkably adaptable sonic character, due to its selectable tube and semi-conductor output stages, as well as its switchable D/A converters."

Fully Balanced Design

The Pre Box RS Digital boasts a fully balanced dual mono design with separate 'mirrored' circuitry for each channel. This approach yields superior channel separation and, when done right as with the Pre Box RS Digital, it also offers superb soundstage and imaging. The Class-A circuitry with no negative feedback ensures pristine audiophile performance. To suit your music and your mood, you can select to use either the tube or solid-state output stage.

Reference Class DAC

In addition to its outstanding performance as a preamp, the Pre Box RS Digital is a reference-class D/A converter for a wide range of digital audio stereo sources. It superbly acts as a superior USB audio interface for demanding computer audio. It also features an AES/EBU input as well as an I²S interface for use with the Pro-Ject CD Box RS CD transport.

Full DSD Capability

For the cutting-edge audiophile, the DAC Box RS provides full DSD capability (up to DSD128) over PCM. All inputs fully support 24-bit/192 kHz HD music data (optical inputs support 96/24) in fully asynchronous mode for outstandingly pure, low jitter, low distortion digital audio.

Selectable Tube or Solid State Output Stage

The DAC Box RS offers a high degree of flexibility in sound quality by offering both a vacuum tube and a solid state output stage, so that you can choose the audio 'feel' you want to suit the type of music and recording that you listen to. For warmer and more relaxed sounding audio, choose the 6922 tube output stage. Or choose the solid state ‘Class A’ output stage with incredible details and dynamics. A first-class headphone output with selectable impedance provides a perfect match to your headphones.

In addition to the two outputs stages, a choice of two different digital filter settings allow you to tailor the sound to suit your preferences.

Nine Digital Inputs

The nine digital inputs consist of two coaxial (S/PDIF), four Toslink optical, one USB B, and one AES/EBU. Additionally, an I²S interface and clock output are for use with the Pro-Ject CD Box RS CD transport. Analog outputs consist of one pair of balanced XLR outs and one pair of unbalanced RCA outs. An outboard power supply keeps noise to a minimum. As an upgrade you can also use a separately available optional outboard power supply for enhanced sound quality.

Perfect Partner for Pro-Ject CD Box RS

The Pre Box RS Digital offers three-dimensional sound-staging, perfect micro dynamics, and ultimate resolution combined with the flexibility of connection to a wide range of digital and one analog sound sources. It makes the perfect partner for the Pro-Ject CD Box RS disc drive, connecting to it via as I²S connection provided via RJ45 for jitter-free disc playback.

Product made in Czech Republic.

Overview

• Hybrid vacuum tube/solid state DAC, line level preamp, premium headphone stage
• Selectable solid-state and tube output stages
• State-of-the-art PCM1792 DAC chips from Texas Instruments
• Fully balanced dual mono design
• Class-A circuitry with no negative feedback
• Full DSD capability (up to DSD128) over PCM.
• Choice of two different digital filter settings
• Nine digital inputs
• 6922 EH tube output stage

• Digital inputs: 1 x USB 2.0, 2 x S/PDIF, 4 x S/PDIF Optical, 1x AES/EBU balanced, 1 x RJ45 Sonic I2S for CD Box RS
• Analog input: 1 pair unbalanced RCA line level inputs
• Analog outputs: 1 pair balanced XLR, 1 pair unbalanced RCA, 1/4" headphone jack

• DAC1: 2 x PCM1792 24/192
• DAC2: PCM5102 32/384
• Digital inputs: 1 x USB 2.0 Audio 32/384 + DoP-DSD 64/128; 1 x RJ45 Sonic I2S for CD Box RS in Sonic Mode; 2 x S/PDIF 24/192; 4 x S/PDIF Optical 24/96; 1x AES/EBU balanced 24/192
• Input impedance: 33k ohms
• Headphone impedance: 5 / 20 / 50 ohms switchable
• Analog input sensitivity: 1.6V RMS for full headphone output
• Frequency response: 2 0Hz – 50 kHz (+ 0/- 0,1 dB)
• Signal to noise ratio: -100dB (IEC-A)
• THD: 0.005% solid state output/ 0,25% tube output
• Master clock output: 16,9344MHz for CD Box RS in Sonic Mode
• Outboard power supply: 20V/3A DC
• Power consumption: 300mA solid / 850mA tube / 90mA standby
• Dimensions: 8.1" wide, 2.8" high, 7.9" deep (8.25" deep with connections)
• Weight: 4.3 lb without power supply

"Outstanding" Rating

Extremely compact, and for its size an almost sensationally equipped DAC-preamp. It has a remarkably adaptable sonic character, due to its selectable tube and semi-conductor output stages, as well as its switchable D/A converters.

- Germany's StereoPlay magazine, June 2014