Pro-Ject Amp Box DS2 black

With 100 watts per channel into 8 ohms in a chassis 20 cm wide, the Pro-Ject Amp Box DS2 delivers on a rare promise: that of a stereo power amplifier capable of driving demanding speakers without taking up all the space in a hi-fi cabinet. As the successor to the Amp Box DS, it benefits from a four-layer printed circuit board that shortens signal paths and reduces distortion. The result is a compact, understated, and efficient unit that integrates into a separate Pro-Ject system or into any hi-fi setup built around an external preamplifier.

Class D amplification designed for musicality

The Amp Box DS2’s Class D amplification module delivers 2 × 100 W into 8 ohms and 2 × 140 W into 4 ohms, figures sufficient to fill an average-sized living room with sound using most compact speakers or floorstanding speakers on the market. The frequency response extends from 10 Hz to 50 kHz (-3 dB), leaving a comfortable margin beyond the audible spectrum.

Total harmonic distortion remains below 0.1% at 90 W, and the noise floor exceeds 90 dB: two measurements that reflect a clean signal, even at high volume. The frequency response is load-independent, which means the amplifier’s behavior varies little depending on the impedance of the connected speakers. Pro-Ject also claims sound tuning inspired by tube amplifiers, aiming to preserve a fluid and spacious presentation rather than a clinical one.

The high efficiency of Class D offers a practical advantage: the Amp Box DS2 generates very little heat, even after several hours of operation. No ventilation or free space around the unit is needed, an advantage for cabinet installations or stacked Box Design enclosures.

A redesigned circuit compared with the Amp Box DS

The move from the Amp Box DS to the DS2 version is not limited to a cosmetic update. The printed circuit board goes from two to four layers, a modification that shortens signal traces and better isolates the sensitive sections of the circuit. This type of design, common in more expensive devices, helps reduce residual noise and interference between amplification stages.

The signal bandwidth is wider and distortion lower than on the previous model, according to data provided by Pro-Ject. The 550 mV input sensitivity (for 100 W into 4 ohms) and 10 kohm input impedance ensure easy compatibility with the vast majority of preamplifiers on the market.

Connectivity and system integration

The Amp Box DS2 features a stereo RCA input and a loop output, which allows the signal to be redirected to another device: a second amplifier, an active subwoofer, or a recorder. This type of output, simple but useful, avoids the need to insert an external splitter.

The speaker terminals accept 4 mm banana plugs, spade connectors, or bare wire. The outputs are isolated, a technical detail that reduces the risk of ground loops between channels and with the other devices in the system.

The trigger input and output (12 V, 2.5 mm coaxial jack) allow synchronized power-on with other elements in the Box Design range, such as the Pre Box DS2 Digital or the Pre Box DS2 Analogue. Simply power on the preamplifier and the Amp Box DS2 turns on automatically, and vice versa when powering off. This daisy-chain operation also works with devices from other brands that use the same 12 V trigger standard.

A compact format that requires a few compromises

The Amp Box DS2 measures just 206 × 68 × 194 mm in its aluminum finish and weighs 1,600 g. This ultra-compact format has direct consequences for the design: the power supply is external. A 48 V / 2.5 A power adapter is included, compatible with 100-240 V / 50-60 Hz mains. The footprint of this external adapter should be taken into account, even though it fits easily behind a piece of furniture.

For those who want to go further, Pro-Ject offers the Power Box DS2 Amp, an external linear power supply with a toroidal transformer. This higher-quality unit, equipped with 40,000 µF of filtering capacity, replaces the original power adapter and can power up to two amplifiers from the DS2 or RS range. The improvement concerns the cleanliness of the current supplied to the amplification module, with an audible effect on dynamics and channel separation according to Pro-Ject.

It should also be noted that the Amp Box DS2 is a pure power amplifier: no volume control, no source selection, no built-in digital-to-analog converter. It requires a preamplifier upstream. This is a deliberate choice in the modular philosophy of the Box Design range, where each function is assigned to a dedicated enclosure.

Technical specifications

Key features

• Premium-quality Class D modules
• Impressive signal spectrum and reduced distortion
• High efficiency from mains power to audio output
• Low heat generation
• Stereo line-level input (RCA)
• Loop output (RCA)
• Isolated speaker outputs
• Trigger input and output
• Elegant aluminum / metal sandwich chassis

Audio performance

• Output power: 2 x 100 W / 140 W into 8 / 4 ohms
• Frequency response: 10 Hz - 50 kHz (0 dB, -3 dB)
• Channel separation: > 40 dB at 20 kHz
• Noise floor: > 90 dB
• Total harmonic distortion (THD): < 0.1% at 90 W
• Gain: 31 dB

Connectivity and inputs / outputs

• Line-level input: 1 pair of RCA (loop-through input-output)
• Input sensitivity: 550 mV (100 W, 4 ohms)
• Input impedance: 10 kohms
• Speaker output: Ø 4 mm terminals for banana plugs, spades, or bare wires
• Trigger: 12 V switching voltage
• Trigger input and output: 2-pole coaxial jack Ø 2.5 mm

Power supply

• External power supply: 48 V / 2.5 A DC
• Mains voltage: 100 - 240 V, 50 / 60 Hz

Dimensions and weight

• Dimensions (W x H x D) 206 x 68 x 194 mm
• Weight 1600 g