Pro-Ject Phono Box S2 Ultra Phono Preamplifier - Silver

A Phono Stage Built All Discrete Circuitry - No Op-Amps

The Pro-Ject Phono Box S2 Ultra is a compact MM/MC phono preamplifier. It replaces both of Pro-Ject's earlier DS and DS+ phono stages, stepping up to a fully discrete circuit design.

Most phono preamps at this price rely on operational amplifier chips to do the work. The S2 Ultra skips them entirely. It builds its RIAA correction from discrete transistors instead.

That RIAA correction is also split. Rather than applying the full curve in one pass, the S2 Ultra corrects it in stages, aiming for a more accurate result across the audible range.

Polystyrene capacitors, prized by many audiophiles for their stability and low distortion, appear throughout the signal path. A solid metal casing shields the circuit from outside interference.

Pro-Ject positions the S2 Ultra as an entry point into serious phono design. It's built for listeners who've outgrown a basic phono stage. It's also for anyone not ready to spend on a flagship model yet.

Precisely Match Your Phono Cartridge Settings

Gain switches across four levels: 40dB, 43dB, 60dB, and 63dB, covering everything from a high-output moving magnet to a low-output moving coil cartridge.

Input impedance switches between 10, 100, and 1,000 ohms, plus the standard 47 kOhm setting for moving magnet cartridges. Input capacitance switches between 100pF and 220pF.

A switchable subsonic filter cuts rumble below 20Hz at -18dB, useful on a warped record or a turntable prone to footfall. Signal-to-noise ratio reaches 89dB on the moving magnet setting, with THD rated at just 0.00052%.

It measures 103 by 37 by 119mm. It weighs 570 grams without its included 18V power supply. An outboard Accu Box S2 battery supply is available as a separate upgrade. It replaces the standard wall-wart supply with a cleaner DC source.

Who Is This Preamp Best For?

• Anyone who owns a moving coil cartridge. Its 60dB and 63dB gain settings give low-output MC cartridges the boost they need.
• Listeners who want to fine-tune their setup. Switchable gain, loading, and capacitance let you dial the preamp in to your exact cartridge.
• Anyone curious about op-amp-free circuit design. Its fully discrete architecture is a genuine step up from typical entry-level phono stages.
• Shoppers who might upgrade their power supply later. The optional Accu Box S2 battery supply drops right in without swapping preamps.
• Not the right fit for anyone who wants large, easy-to-reach controls. The gain and loading switches are small rear-panel dip switches, not front-panel knobs.

How Does It Connect to Your System?

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

Set the rear dip switches for gain, loading, and capacitance to match your specific cartridge before you start listening. Your cartridge's manual will list its recommended settings, and getting them right makes a real difference in tonal balance.

Plug in the included 18V power supply, or add the Accu Box S2 battery supply later for a quieter DC source.

Pairs Well With

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

• 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
• Audio racks to keep it near your turntable

Frequently Asked Questions

How is this different from the standard Phono Box S2?

The standard S2 uses op-amp circuitry. The Ultra replaces that with a fully discrete design and adds split RIAA equalization for extra accuracy.

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.

Can I upgrade the power supply later?

Yes. The S2 Ultra is compatible with Pro-Ject's optional Accu Box S2 battery supply, sold separately.

What colors is it available in?

Silver and black are both available.

What's the warranty?

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

See It in Action

Henley Audio, Pro-Ject's UK distributor, introduces the Phono Box S2 Ultra:

Gadget Jungle Pro takes a closer look at the S2 Ultra:

Why Audio Advisor?

• 40+ Years of Expertise — Since 1981, we’ve helped over a million music lovers find the right gear.
• 60-Day Money-Back Guarantee — Take your time. Listen, enjoy, and make sure it’s right for you.
• Real Experts, Real Help — Our team is here to answer your questions at 800-942-0220, weekdays 9am–6pm EST.
• Free Shipping — On orders over $49, delivered to your door.
• Flexible Payment Options — Financing available so you can start listening now.

Learn More

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