Pro-Ject Tube Box S2 Phono Preamplifier - Silver

A Little Tube Warmth for Your Vinyl

The Pro-Ject Tube Box S2 is an MM/MC phono preamplifier built around a pair of real vacuum tubes. It's a different approach from Pro-Ject's solid-state Phono Box line, aimed at listeners who want some tube character in their sound.

Two ECC83 (12AX7A) tubes handle the gain stage. They're user-replaceable, so you can swap in a different tube later to tune the sound to your taste, a hobby some vinyl fans call tube rolling.

This is a more affordable sibling to Pro-Ject's Tube Box DS2, which steps up to a larger hybrid design in a different chassis. The S2 keeps things simpler, with a single pair of RCA connections for both input and output.

Dialed In for Your Exact Cartridge

Gain switches across five levels: 40dB, 43dB, 50dB, 60dB, and 63dB, covering everything from a moving magnet to a moving coil cartridge.

Input impedance switches between 10, 100, 1,000, and 2,000 ohms for moving coil cartridges, plus a fixed 47 kOhm setting for high-output MC and MM cartridges. Input capacitance switches across six steps from 47pF to 587pF.

A subsonic filter cuts rumble below 20Hz at 18dB per octave, useful on a warped record or a turntable prone to footfall. Signal-to-noise ratio reaches 77dBA, with THD rated under 0.0025%.

It measures 103 by 73 by 131mm and weighs 410 grams without its included 18V power supply. An outboard Accu Box S2 battery supply is available as a separate upgrade.

What Reviewers Are Saying

Caleb Attaway reviewed the Tube Box S2 for Analog Planet in March 2020. Comparing it to a built-in phono stage, he found "a little better bass, maybe a bit more defined detail," along with a "little wider soundstage presentation."

Rick Coste reviewed it for The Joy of Vinyl in May 2023, describing its sound as "warm, captivating, and detailed." He also praised its "excellent instrument separation and impressively quiet background."

Who Is This Preamp Best For?

• Anyone curious about tube sound. Its two ECC83 tubes bring a warmer character than a typical solid-state phono stage.
• Listeners who enjoy tinkering. User-replaceable tubes let you experiment with different tube types down the road.
• Owners of both MM and MC cartridges. Switchable gain and loading cover either type.
• Shoppers who want proven, independently reviewed sound quality. Multiple named reviewers praised its warmth and detail.
• Not the right fit for anyone who wants zero maintenance. Tubes wear out eventually and need replacing, unlike a solid-state design.

How Does It Connect to Your System?

Run your turntable's phono cable into the Tube Box S2's RCA input, then connect its RCA output to a line-level input on your amplifier or receiver.

Set the rear switches for gain, loading, and capacitance to match your cartridge before you start listening. Give the tubes a few minutes to warm up for their best sound.

Pairs Well With

Building your system? Here are some great companions for the Pro-Ject Tube Box S2:

• Turntables without a built-in phono stage
• Phono cartridges, MM or MC, matched to its switchable gain
• Interconnect cables to connect its output to your amp

Frequently Asked Questions

What tubes does it use?

Two ECC83 (12AX7A) tubes. They're user-replaceable, so you can swap in a different tube as they wear out or to experiment with the sound.

How is this different from the Tube Box DS2?

The DS2 is a pricier, larger model in a different chassis. The S2 covers the same MM/MC ground in a simpler, more affordable package.

Can I use this with a moving coil cartridge?

Yes. Its 60dB and 63dB gain settings, along with lower loading options, are built with moving coil cartridges in mind.

What's the warranty?

Pro-Ject covers the Tube Box S2 with a two-year warranty, extendable to three years with product registration.

See It in Action

This Does Not Compute puts the Tube Box S2 through a full review:

HIFI Daydreaming compares it against a Rega phono stage:

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Learn More

Want to learn more about tube versus solid-state phono stages, matching a preamp to your cartridge, or getting the most from your vinyl collection? Visit our Learning Center for guides, tips, and expert advice.