Pro-Ject AMP Box S3 CI Stereo Power Amplifier

With the Amp Box S3 CI, Pro-Ject Audio Systems expands its popular compact amplifier series with a variant specifically designed for custom installations. It combines the audiophile sound philosophy of the classic Amp Box models with features specifically designed for automated systems, multi-room solutions, and professional installations.

The result is a versatile, extremely compact power amplifier that can be seamlessly integrated into modern smart home, studio or home cinema environments – without sacrificing musical quality.

Designed for custom installation

The Amp Box S3 CI was specifically designed for integrators and complex installation environments. Multiple intelligent control functions enable reliable automation within modern AV and smart home systems.

The auto-power function ensures that the device switches on automatically as soon as it is supplied with power.

Additionally, the signal-sensing technology detects whether an audio signal is present at the input and activates or deactivates the amplifier accordingly. This allows the power amplifier to operate completely automatically – ideal for concealed installations or systems without direct access.

Another key feature is the RS232 interface, a widely used control protocol in custom installations. It enables integration into automation solutions and centralized control within smart home or home theater systems.

Flexible sound tuning

For precise adjustment to a wide variety of loudspeakers and room sizes, the Amp Box S3 CI has integrated controls for level, bass and treble.

These adjustment options allow for quick fine-tuning of the frequency response and make the amplifier particularly flexible – regardless of whether it is used in a living room, studio, restaurant or conference room.

Professional connectors also ensure a secure connection of the cables and prevent accidental disconnection – an important detail for installations in hard-to-reach areas.

High-quality amplifier architecture

Inside, it uses the same modern circuit board design as the Amp Box S3. The revised circuit topology significantly reduces distortion and improves the signal-to-noise ratio.

During development, a special focus was placed on musical naturalness: The sound characteristics were tuned to approximate the warm, organic sound of classic tube amplifiers – combined with the efficiency and reliability of modern transistor technology.

Compact, robust and low-interference

The Amp Box S3 CI is housed in a solid, all-aluminum enclosure. This reliably protects the electronics from mechanical vibrations and electromagnetic interference such as EMI and RFI radiation – a crucial advantage in complex installation environments with many electronic devices.

Thanks to its extremely compact dimensions, the power amplifier can be easily integrated even where space is limited – for example in technical cabinets, rack systems or hidden installations.

At the same time, the minimalist design impresses with its precisely crafted aluminum surfaces. When the amplifier is visibly used in studio or home theater environments, it blends harmoniously into modern hi-fi setups.

Typical areas of application

• The versatile features open up numerous application possibilities:
• HiFi amplifier with tone control for rooms of approx. 10–15 m²
• Amplifier solution for modern streaming systems
• Desktop amplifier for studio near-field monitors
• Multiroom audio installations
• Performance upgrade for home theater power amplifiers
• Amplifiers for wall or ceiling-mounted speakers
• Smart home integration via RS232
• Installations in hotels, lobbies or conference areas
• Audiophile sound systems for restaurants and cafes

TECHNICAL DATA

• Output power: 2 × 20 W at 8 ohms / 2 × 37 W at 4 ohms
• Peak power: 2 × 50 W at 4 ohms
• Frequency response at 20 Hz: Bass EQ variable ±11 dB
• Frequency response at 20 kHz: Variable treble EQ ±5 dB
• Channel separation: -68 dB at 10 kHz
• Signal-to-noise ratio: 88 dBV (95 dBV A-weighted)
• Total Harmonic Distortion (THD): <0.03% at 5W
• Gain: 37 dB (level at maximum)
• Input: 1 pair of RCA/Cinch jacks
• Speaker connections: 4-pin Phoenix block
• 12V trigger: In & Out, 2-pole jack socket Ø 2.5 mm
• Power supply: 20 V / 3 A DC (universal power supply)
• Dimensions (W × H × D): 103 × 36 × 112 mm (incl. connections)
• Weight: 380 g (without power supply)