Pro-Ject Phono Box DS3 B - Balanced Phono Preamplifier

Balanced Phono Performance at an Accessible Price

The Pro-Ject Phono Box DS3 B is an MM/MC phono preamplifier built around a fully balanced circuit. Pro-Ject positions it between the unbalanced Phono Box S3 B and the flagship Phono Box RS2.

This is the solid-state DS3 B, distinct from the similarly named Tube Box DS3 B, which uses vacuum tubes in its gain stage instead. The two share a naming convention but not a circuit.

Pro-Ject describes the DS3 B as bringing some of the high-end features of the flagship RS2 down to a more accessible price, largely by offering true balanced operation without RS2-level extras like a DECCA curve or channel balance control.

Fully Balanced, Finely Adjustable

Gain switches across six levels: 40, 45, 50, 55, 60, and 65dB, usable for either moving magnet or moving coil cartridges.

Input impedance is continuously adjustable from 10 to 1,000 ohms for moving coil use, or switchable to a fixed 47 kOhm setting for moving magnet. Capacitance switches across four steps: 50, 150, 300, and 400pF.

RIAA accuracy is rated better than ±0.25dB from 20Hz to 20kHz. THD stays under 0.001% on moving magnet and under 0.004% on moving coil, both at 1kHz. A switchable subsonic filter cuts rumble below 20Hz at 18dB per octave.

Inputs include a 5-pin mini XLR connection along with a pair of full-size XLR and a pair of RCA jacks. It measures 206 by 72 by 194mm and weighs 1,480 grams without its power supply.

What Reviewers Are Saying

James Michael Hughes reviewed the DS3 B alongside Pro-Ject's X8 turntable for StereoNET in May 2022. He found the pairing's sound "clear, open and detailed," putting it "very much on a par" with a well-regarded reference phono stage.

He specifically credited the DS3 B's balanced operation for "a 6dB increase in output level and a bigger and more dynamic sound, with much greater breadth and depth."

Who Is This Preamp Best For?

• Anyone building a balanced XLR system on a moderate budget. It brings true balanced operation without the flagship RS2's price.
• Owners of both MM and MC cartridges. Six gain settings and continuously variable loading cover a wide range of both.
• Listeners who want proven, independently reviewed performance. A named reviewer praised its detail and the audible benefit of its balanced design.
• Collectors who want fine cartridge-matching control. Continuously variable MC loading beats a handful of fixed steps.
• Not the right fit for anyone who wants tube sound. The similarly named Tube Box DS3 B uses vacuum tubes instead of this model's solid-state circuit.

How Does It Connect to Your System?

Run your turntable's cable into the DS3 B's RCA or XLR input, matched to your tonearm's cable. Connect its RCA or XLR output to your amplifier the same way.

Set gain, loading, and capacitance to match your cartridge before you start listening.

Pairs Well With

Building your system? Here are some great companions for the Pro-Ject Phono Box DS3 B:

• Turntables with a balanced tonearm output to take advantage of its XLR input
• Phono cartridges, MM or MC, matched to its switchable gain
• Preamplifiers with balanced XLR inputs
• Interconnect cables, balanced or unbalanced, to connect its outputs

Frequently Asked Questions

How does this compare to the Phono Box S3 B and RS2?

The S3 B is unbalanced and sits below it. The RS2 sits above it, adding a DECCA equalization curve and a channel balance control that the DS3 B doesn't include.

Is this the same as the Tube Box DS3 B?

No. They share a naming pattern, but the Tube Box DS3 B uses vacuum tubes in its gain stage. This model is solid-state.

Do I need a balanced tonearm cable to use this?

No. Standard RCA inputs and outputs are included alongside the XLR connections, so it works with an unbalanced turntable too.

What's the warranty?

Pro-Ject covers the Phono Box DS3 B with a two-year warranty, extendable to three years with product registration.

See It in Action

Audio Center Poland unboxes the DS3 B:

Gramophone takes a closer look at the DS3 B:

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Learn More

Want to learn more about matching a phono preamp to your cartridge, balanced connections, or getting the most from your vinyl collection? Visit our Learning Center for guides, tips, and expert advice.