Pro-Ject Power Box DS2 AMP black

The compact amplifiers in Pro-Ject’s Box Design range come with switching power supplies. Functional as they are, they remain a compromise. The Power Box DS2 Amp replaces them with a regulated linear power supply, featuring a high-capacity toroidal transformer and an oversized filtering stage. The principle is simple: provide cleaner, more stable current to DS2 and RS series amplifiers so they can operate under better conditions.

Why replace a switching power supply

The switching power supplies fitted to the Amp Box DS2, DS2 Mono, Amp Box RS, RS Mono, and Stereo Box RS are compact and lightweight, but they generate residual electrical noise related to their switching frequency. This noise, while not always blatantly audible, can appear as a veil over the sound reproduction, a loss of micro-detail, or a slightly elevated noise floor.

A linear power supply operates on a different principle: a transformer directly steps down the mains voltage, without a high-frequency switching stage. The result is DC current that is both cleaner and less affected by interference from the household electrical network (dimmers, computer equipment, LED lighting).

A copper-shielded toroidal transformer

At the heart of the Power Box DS2 Amp is a large toroidal transformer whose primary and secondary windings are separated by a copper shield. This copper sheet acts as an isolation screen that blocks interference from the electrical grid before it reaches the amplifier circuit. The transformer has a high power reserve compared with the original power adapter: it delivers 2 × 48 V at 2.5 A, enough to power a stereo amplifier or two mono blocks.

The output impedance is very low, which means the power supply responds quickly to the amplifier’s current demands. On musical passages with high dynamics, deep bass, or fast transients, this responsiveness can translate into better control and a firmer foundation in the lower part of the spectrum.

40,000 µF filtering and controlled residual ripple

The filtering stage relies on low-ESR capacitors (low equivalent series resistance) totaling 40,000 µF of capacitance. This generous sizing smooths the rectified current and reduces residual ripple to 7 mV, a very low level for a power supply in this category. In practice, the noise floor of the powered amplifier is lowered, benefiting the intelligibility of low-level details and the separation of sonic layers.

Five compatible Pro-Ject amplifiers

The Power Box DS2 Amp works with five Pro-Ject amplifier models, all powered at 48 V: the Amp Box DS2 (stereo), Amp Box DS2 Mono, Amp Box RS (stereo), Amp Box RS Mono, and Stereo Box RS. Its two outputs allow connection of either one stereo amplifier or two mono blocks. The combination of one stereo amplifier and one mono block on the same unit is not permitted by Pro-Ject. Two connection cables are supplied. For going further, Pro-Ject offers the Connect it Power RS/DS cable, featuring enhanced shielding and available in custom lengths.

The unit includes a 12 V trigger output, controlled by the front-panel switch. It allows the connected amplifier to be turned on or off automatically, or the power-up of several DS2 range devices equipped with trigger inputs to be chained.

Not to be confused with the Power Box DS2 Sources, which is the Pro-Ject linear power supply dedicated to source devices (turntables, phono preamplifiers, DACs, CD players) and delivers different voltages (9 V, 15 V, 18 V).

Design and finishes

The chassis is made of aluminum, in the usual dimensions of the Box Design DS2 range: 206 × 71 × 209 mm for the standard version, 240 × 72 × 209 mm with the wooden side panels. Weight reaches 4.2 kg in the aluminum version and 4.8 kg with the wooden side panels, a sign of the mass of the transformer inside. Two basic finishes are available, silver and black. The real wood side panels (rosewood, walnut, or eucalyptus) are optional and magnetically attach to the sides of the chassis, as with the entire DS2 series.

The mains input uses an IEC C15 connector, the high-temperature notch model found on some amplifiers and devices with high heat dissipation. Input voltage is 230 V / 50 Hz in the European version (120 V / 60 Hz for the North American market).

Installation precautions

Pro-Ject recommends not stacking the Power Box DS2 Amp on the amplifier it powers (or vice versa). The toroidal transformer generates a magnetic field that, at short distance, can induce interference in the amplifier circuits, including digital class D amplification models. Physical spacing between the two devices, or side-by-side placement, is enough to avoid this problem. The product is made in Europe.