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Pro-Ject Uni Box S3 Integrated Strreaming Amplifier
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Pro-Ject Uni Box S3 Integrated Strreaming Amplifier
Pro-Ject Uni Box S3 Integrated Strreaming Amplifier
Black
22 Saint Kilda Road
22 Saint Kilda Road
Suite 2.02
St Kilda VIC 3182
Australia
Pro-Ject
Uni Box S3 Integrated amplifier with modern streaming
Analogue and streaming done right
The Uni Box S3 dares to break away from the norm, redefining what a modern streaming amplifier can be. While many amplifiers are dominated by deeply integrated streaming tech – compromising their core design – the Uni Box S3 takes a different path.

The Master of Analogue & Digital
The Uni Box S3 masterfully bridges the worlds of analogue and streaming. Your analogue sources - like turntables - are not digitized, preserving their rich and lifelike sonic character. With a fully analogue pre- & and power amp design, every nuance of your music is delivered with breathtaking punch and dynamic precision. At Pro-Ject Audio Systems, our mastery of analogue hardware design allows us to craft an astonishingly powerful amplifier within the sleek, compact aluminium case of the Uni Box S3. All this power remains usable entirely without a mobile app or the need to constantly update software.

The Uni Box S3 allows you to stream any of your connectected devices – turntable, CD player or even TV – to other compatible streamers*.

Market leading streaming
Partnering with WiiM, the Uni Box S3 streaming technology is powered by the industry leading WiiM OS™. The Cirrus Logic CS4344 DAC offers a high quality resolution of up to 24bit and 192kHz.
With the Pro-Ject Home app you control the streaming options on input 8 - the streaming input. Setting up the WiFi connection is a breeze. Just open the app and it automatically detects your new Uni Box S3 and walks you through the setup process. Comfortably reset the WiFi connection via long press of the Stream button on the front panel.
The Uni Box S3 even allows you to stream any of your connected devices - turntable, CD player or even TV - to other compatible streamers*.
*Compatible with Uni Box S3. Compatible with Stream Box E, Stream Box S3 & Wireless Box E available later in 2025.
| Tubes | 2 x ECC83 (12AX 7A) |
| Input impedance | 10 ohms, 100 ohms, 1 kohm, 2 kohms |
| Input capacitance/impedance | 47pF, 147pF, 267pF, 367 pF, 487 pF and 587 pF* / 47 kohms |
| Input gain | 40 dB, 43 dB / 50 dB, 60 dB und 63 dB |
| Noise floor | 77 dB (A weighted) at 40 dB input gain, 65dB (A weighted) at 50 dB and 63 dB input gain |
| THD | <0.03% at 40 dB input gain <0.07% at 50 dB and 63 dB input gain |
| RIAA-equalisation curve accuracy | +/- 0.5 dB/20 Hz - 20 kHz |
| Subsonic filter | at 20 Hz with 18 dB/octave |
| Input | 1 pair RCA/phono sockets |
| Line-level output | 1 pair RCA/phono sockets |
| Outboard power supply | 18 V / 1.000 mA DC, suitable for your country's mains supply |
| Power consumption | 470 mA DC, <1W in standby |
| Dimensions W x H x D with sockets | 103 x 73 x 131 mm |
| Weight | 450 g without power supply |
User Reviews
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