Pro-Ject Audio Systems has introduced two new headphone amplifiers, the Head Box DS3 B and the Head Box S3 B, that aim to bring fully balanced audio to a wider range of headphone listeners. These two compact models are the first in a revamped series of electronics that update Pro-Ject’s long-standing “Box Design” line, and they’re built for people who want serious sound quality without taking up too much space, or spending a fortune.

If you're a dedicated headphone listener, working from a desk setup, or just looking to get more out of your wired cans, both amps promise cleaner sound and better control, especially if you're using harder-to-drive headphones.

Pro-Ject’s Box Design series has been around since the early 2000s, offering compact alternatives to traditional hi-fi gear. Instead of the typical full-width components, these models use smaller enclosures and external power supplies, which can help reduce electrical noise and simplify placement on a desk or shelf.

The DS3 B and S3 B carry that same DNA. They’re housed in all-metal enclosures, built in the EU, and designed to work with both balanced and unbalanced headphone setups. But this time around, Pro-Ject isn’t just adding balanced connectors—they’ve gone for fully balanced circuitry, which is a key feature that sets these apart from many other amps in this price range.

You’ll often see headphone amps with XLR or 4.4mm outputs labeled as “balanced,” but in a lot of cases, those amps are still running unbalanced circuits internally. What you’re getting is a mirrored signal, not a truly separate left/right path.

Pro-Ject takes a different approach here. The Head Box DS3 B and S3 B are designed with true balanced signal paths, meaning the internal circuitry keeps the left and right audio channels isolated from input to output. That design can help reduce background noise, increase channel separation, and improve the overall clarity of your music.

To get the full benefit of this, you’ll need a pair of headphones with a balanced connection, like a 4-pin XLR or 4.4mm Pentaconn plug. But even if you’re using standard 3.5mm or 6.3mm connectors, you can still take advantage of the extra power and refinement these amps offer.

While the DS3 B and S3 B look similar on the outside and share a lot of core features, they’re built a little differently under the hood, and that’s where you’ll notice the biggest differences.

Head Box S3 B:

• Uses a pair of TPA6120A2 amplifier chips from Texas Instruments
• Outputs up to 820mW into 30 ohms (balanced)
• Designed for most headphones on the market—Pro-Ject estimates around 98% will be a good fit
• Has RCA and XLR inputs, plus balanced and unbalanced headphone outputs
• Priced at £329 / €399

This one’s the more affordable of the two and makes a great entry point for someone who wants to try balanced audio without spending top dollar. It’s also compact enough to live comfortably on a desktop setup.

Head Box DS3 B:

• Uses a fully discrete amplifier stage, rather than integrated chips
• Offers up to 1.5W into 30 ohms (balanced)
• Geared toward planar magnetic or low-sensitivity headphones that need more power
• Also includes RCA/XLR inputs and balanced/unbalanced outputs
• Priced at £629 / €699

The DS3 B steps things up with more headroom and a different sound profile. Pro-Ject describes it as having more “warmth and authority,” which might appeal to listeners with high-end headphones or a more demanding taste in music.

One thing Pro-Ject is emphasizing with these amps is usable power, not just big numbers on a spec sheet. According to the company, some brands publish eye-catching wattage figures that don’t always translate to great sound quality. Instead of chasing raw output, Pro-Ject focused on clean, controlled delivery that can actually make a difference when you’re listening.

So while 820mW or 1.5W might not sound huge compared to some figures you’ll see online, these amps are designed to provide enough juice to drive most headphones well—without introducing distortion or draining dynamics.

Both amps offer a good amount of flexibility when it comes to connecting your gear. You’ve got RCA and XLR inputs for plugging in a DAC, streamer, or preamp, and outputs for just about any pair of headphones you might own: 3.5mm, 6.3mm, 4.4mm Pentaconn, and 4-pin XLR.

Whether you're listening on a high-end planar set at home or a mid-range pair of dynamic headphones at your desk, these amps can fit in without needing to overhaul your entire audio setup.

The Head Box S3 B and Head Box DS3 B are both available in either black or silver finishes and share the same compact chassis design found in the rest of Pro-Ject’s S3 and DS3 product lines. They’re available now through Pro-Ject dealers in Europe, with US pricing and availability still to be announced.

• Head Box S3 B – £329 / €399
• Head Box DS3 B – £629 / €699

In the meantime, you can check out other Pro-Ject gear from the Box Design line at Crutchfield.

Pro-Ject’s new headphone amps bring real balanced performance into the spotlight, without requiring a full-size rack or sky-high budget. If you’ve been curious about going balanced, or just want a clean, capable amp that won’t clutter your desk, the S3 B and DS3 B offer two solid options. One is an approachable starting point. The other is more tailored for listeners with power-hungry headphones or more demanding gear.

Either way, they both reflect a broader shift toward compact, high-performance desktop setups that don’t skimp on audio quality.

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