Pro-Ject Pre Box RS2 Digital - Balanced Preamplifier with DAC- Silver

Pro-Ject Pre Box RS2 Digital Balanced Preamplifier with DAC

What You Need to Know

Two Preamplifiers in One: Solid-State or Tube, at the Push of a Button

The Pro-Ject Pre Box RS2 Digital packs a fully balanced, dual-mono DAC and preamplifier into a chassis barely 8 inches wide—then adds something no rival offers at the price: a genuine tube output stage you can switch in or out from your listening chair. It earned the EISA Best Product award (2019–2020, with its matching CD transport) and Hi-Fi News’ “Outstanding Product” badge.

Available in black or silver aluminum.

The Tube Stage: Real Glass, Really Balanced

Four Electro-Harmonix 6922 tubes power a discrete, fully balanced tube output buffer—not a token single-tube buffer, but a true balanced stage. Press the Tube button on the remote and after a 30-second warm-up the sound takes on the sweetness, roundness, and dimensionality only tubes deliver; the tubes stay heated afterward, so you can compare tube and solid-state instantly.

The unit even remembers your choice at power-up. Two distinct amplifiers, one box—match the character to the music.

True Dual-Mono Balanced DAC

Conversion is handled by two 32-bit ESS Sabre ES9038Q2M DACs—one per channel—in a fully balanced double-mono layout with separate left and right signal paths from input to output. Dynamic range measures 124dB, with channel separation beyond 117dB.

Every Format, Your Choice of Filters

PCM plays to 32-bit/768kHz and DSD to DSD512, with full MQA decoding on every digital input. Eight selectable digital filters, optional upsampling, and selectable re-clocking modes let you fine-tune playback, all shown on a crisp 3.5-inch color display. It’s Roon Tested and certified for Audirvana.

Nine Digital Inputs—Including I²S with Master Clock

Beyond USB, two optical, coax, AES/EBU, and aptX Bluetooth, the Pre Box RS2 Digital offers an I²S connection over HDMI plus a dedicated master-clock output—a jitter-killing direct link designed for Pro-Ject’s CD Box RS2 T transport. Balanced XLR and RCA analog inputs make it a complete system preamp, with variable XLR and RCA outputs plus 12V trigger in and out.

A Serious Headphone Amplifier, Too

The front-panel headphone output is fully discrete and DC-coupled—no coupling capacitors anywhere in the signal path—delivering 245mW into 32 ohms and driving headphones from 8 to 300+ ohms with speed and purity.

Building Your System

The Pre Box RS2 Digital is designed as the heart of Pro-Ject’s reference RS2 stack: pair it with the CD Box RS2 T transport via I²S and master clock (the EISA-winning combination), feed its variable balanced outputs directly into a power amp or active monitors, and upgrade later with the Power Box RS2 Sources linear power supply in place of the included adapter.

Add Pro-Ject’s Stream Box S2 Ultra for streaming, and a world-class compact system fits on a single shelf.

Features & Specifications

Switchable Tube or Solid-State Output
Four 6922EH tubes in a fully balanced buffer, remote-selectable.

Dual-Mono ESS Sabre ES9038Q2M DACs
One 32-bit DAC per channel; 124dB dynamic range.

Hi-Res Everything
32-bit/768kHz PCM, DSD512, full MQA on all inputs; Roon Tested.

Nine Digital Inputs
USB, I²S/HDMI with master clock, AES/EBU, coax, 2x optical, Bluetooth aptX.

Discrete DC-Coupled Headphone Amp
No coupling capacitors; 245mW into 32 ohms.

Upgradeable Power Supply
Step up to the Power Box RS2 Sources linear PSU anytime.

Specifications

•          Type: Balanced Preamplifier / DAC / Headphone Amplifier

•          DAC: 2 x ESS Sabre ES9038Q2M (dual mono, 32-bit)

•          Output Stage: Switchable Solid-State or Tube (4 x 6922EH)

•          PCM Support: Up to 32-bit/768kHz

•          DSD Support: Up to DSD512

•          MQA: Full Decoding on All Digital Inputs

•          Digital Inputs: USB-B, I²S (HDMI), AES/EBU, Coax, 2 x Optical, Bluetooth (aptX)

•          Analog Inputs: Balanced XLR, RCA

•          Outputs: Variable Balanced XLR (4V RMS) and RCA (2V RMS); Master Clock Out; Trigger In/Out

•          Headphone Output: 6.35mm, Discrete DC-Coupled; 245mW @ 32 ohms

•          Dynamic Range: 124dB (A-weighted)

•          THD+N: <0.006% (solid-state); 0.017% (tube)

•          Digital Filters: 8 Selectable; Optional Upsampling and Re-Clocking

•          Display: 3.5" Color TFT; Full-Aluminum Remote Included

•          Power: Outboard 20V DC Supply Included (Power Box RS2 Sources upgradeable)

•          Dimensions: 8.1“W x 2.8”H x 8.75"D

•          Weight: 3.78 lbs

•          Finish: Black or Silver Aluminum

•          Warranty: 2 Years Parts & Labor

Frequently Asked Questions

What does the tube stage actually change?
It swaps the discrete solid-state balanced buffer for a genuine four-tube balanced stage. Expect added warmth, sweetness, and dimensionality—and because switching takes one button press, you can match the presentation to each recording.

Can I connect it directly to a power amplifier?
Yes—that’s the design. The variable balanced XLR and RCA outputs drive any power amp or active speakers directly, and the analog XLR/RCA inputs let it serve as your complete system preamp.

Which components is it designed to partner?
Pro-Ject’s CD Box RS2 T transport is the designed-for match, connecting via I²S and master clock—the pairing that won EISA’s Best Product award. The Power Box RS2 Sources linear supply is the factory power upgrade, and the Stream Box S2 Ultra adds streaming.

Who is the Pre Box RS2 Digital designed for?
It’s for the listener who wants a reference-grade balanced DAC, preamp, and headphone amp in one compact chassis—with the rare luxury of choosing between tube and solid-state sound on demand.

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