Pro-Ject calls it the Uni Box S3, and, as the name suggests, it is an all-in-one system featuring an aluminium enclosure in a Box Design format. Into this enclosure, Pro-Ject has managed to pack everything one could ask for from a modern home audio system, for just €799:
- Stereo amplifier,
- MM/MC phono preamp
- DAC
- Streamer,
- HDMI ARC for TV,
- Headphone amplifier
- Multi-room streaming.
Is anything missing? Perhaps a touchscreen. But Pro-Ject’s dynamic boss, Heinz Lichtnegger, argues that touchscreens are great until they fail. According to him, they fail a lot. So the Pro-Ject Home app lets you replace the touchscreen with your phone, offering practical advantages throughout the device’s lifespan.
The front panel retains the Box Design Series usual understated style but is quite informative: on the left, the standby button is accompanied by a blue LED that confirms the device is switched on and starts flashing when mute is active; just below is the 6.3 mm headphone output.
In the centre is the rotary volume knob, which operates a motorised analogue potentiometer rather than a disguised digital control and can also be operated remotely.
On the right, two buttons let you select from the eight available inputs, with a sequence of LEDs that immediately identify the selected source: phono, line, digital, TV or streaming.
In the bottom-right corner, the Stream button lets you pause and resume playback, whilst the adjacent LED indicates the network module's status.
- Flashes green rapidly during start-up;
- Flashes green slowly when the device is ready for setup;
- Flashes yellow slowly when Bluetooth is waiting to pair;
- Alternates rapidly between yellow and green whilst connecting to the Wi-Fi network;
- Remains steady green when the Wi-Fi connection is established;
- Remains steady yellow in Bluetooth mode when already paired;
- Remains steady red in Aux-in mode;
- Alternates slowly between red and green during an OTA update, or whilst resetting to factory settings.
A Quart into a Pint Pot
Pro-Ject has opted for a dual-mono design, with distortion below 0.05% at 10 W/4 ohms, channel separation of 67 dB at 10 kHz, and a signal-to-noise ratio of 94 dB, reaching 97 dB weighted at the power output, according to the manufacturer’s data.
In terms of power, the Uni Box S3 delivers 2 × 23 W into 8 ohms and 2 × 40 W into 4 ohms, measured at 1% harmonic distortion. It is therefore not designed to drive demanding speakers in large rooms. Rather, it is a compact and practical solution for systems in standard domestic spaces.
The Uni Box S3 also features two RCA line inputs and a phono input compatible with MM, MI and high-output MC cartridges, with an impedance of 47 kΩ and a stated gain of 46 dB. This is a significant inclusion for a product in this category.
From LP to Streaming
Pro-Ject is, above all, a turntable manufacturer and has not forgotten that many of its customers still regard vinyl as their preferred source, not merely as a symbolic accessory simply because LPs have come back into fashion.
In the digital domain, the unit offers a coaxial S/PDIF input, two Toslink optical inputs and an HDMI ARC input, the latter designed to integrate the television into the main system without the need for soundbars or other parallel solutions.
The internal converter is a Cirrus Logic CS4344, capable of handling signals up to 24-bit/192 kHz, matching the maximum resolution of the S/PDIF digital inputs.
Miraculously, all this fits into a chassis measuring 206 mm wide, 55 mm high and 153 mm deep — or 176 mm including the connectors — and weighs just 1.1 kg, excluding the external 20 V/3 A power supply.
Analogue to the End
The Austrian brand is keen to emphasise that signals received via the analogue inputs are not converted to digital during the normal amplification process.
In other words, a turntable connected to the phono input, or a CD player connected to one of the line inputs, passes through an analogue pre-amplification circuit to the power stage without ever passing through an A/D converter.
This statement is technically relevant and helps to clear up some confusion that has already begun to circulate in some online reviews. The Uni Box S3 does not use a Class AB power amplifier, as stated in some magazines and forums.
Pro-Ject’s official technical specifications identify the amplification circuit as based on the Texas Instruments TPA3221DDV, a Class D integrated circuit with an analogue input. The distinction is important because, contrary to popular belief, Class D does not mean ‘digital amplification’.
In the case of the Uni Box S3, the signal reaching the power chip remains analogue, although it is from this that ‘Pulse Width Modulation’ (PWM) is generated, which drives the output stage. However, throughout this entire process, there is no conversion of the analogue signal to PCM, nor any intermediate digital processing.
The Uni Box S3 combines analogue pre-amplification with a Class D power stage (with an analogue input), keeping the signal from analogue sources – and only these – intact.
The Uni Box S3 thus mixes modern digital convenience with the classic philosophy of preserving the integrity of analogue sources.
The Postman Always Knocks Twice
There is just one nuance: the unit also functions as a streamer and allows the signal from any physical input to be transmitted over the network to other compatible Pro-Ject or WiiM streamers via the multiroom distribution function.
In this specific case, and solely for network transmission, the analogue signal must be converted to a transportable digital format.
With a Little Help from WiiM
Streaming is provided by the WiiM OS platform and controlled via the Pro-Ject Home app. It supports services including Tidal, Tidal Connect, Spotify Connect, Qobuz, Amazon Music, Deezer and SoundCloud, as well as online radio.
The network connection uses Wi-Fi 5 at 2.4 and 5 GHz. There is also Bluetooth reception, with SBC and AAC codecs. Press releases mention Bluetooth 5.0, while the manual indicates Bluetooth 5.1. For readers, what matters is that it worked without any problems. But not quite as well as Tidal Connect, of course.
The Pro-Ject Home app also adds equalisation functions, allowing you to customise the system’s sound response. This is a feature associated with the digital domain and the streaming platform, not an analogue tone control inserted into the line or phono input path.
Presentation by Alberto Silva and brief audition at Esoterico
In the Esoterico auditorium, if the system were hidden behind a curtain, no one would guess it costs so little. The essence of the music is all there, without tricks or fuss. And the LP ‘Slow Train’ by Hans Theessink sounded complete, with no crackling or hissing. But it was the quality of the streaming of ‘Marais Maison’ by Bertrand Renaudin & Olivier Cahours that impressed me, by which time I was already listening through the 12E Carbon floorstanding speakers, truth be told.
Music Platform
The Pro-Ject Uni Box S3 is not a modern ‘Gaincard’, nor is it a Class AB integrated amp in disguise, let alone a system that digitises everything at the input only to reconstruct the music in software. It is a compact, contemporary Hi-Fi hub that combines streaming and connectivity with an analogue section treated with more respect than is typical in this category. That alone is no small feat.
Uni Box S3 presents itself as a conceptually coherent proposition: digital when suitable, analogue when necessary.
Famous Last Words
In a market where many all-in-one devices sacrifice their soul for convenience, the Uni Box S3 presents itself as a conceptually coherent proposition: digital when suitable, analogue when necessary.
For those who complain that I only write about expensive things, here is an affordable option. Go and have a listen at Esoterico, Grupo JLM, and Imacustica (or your local dealer).
Available in black or silver finishes, the Uni Box S3 has a recommended retail price of €799 at SmartStores.