Pro-Ject Stream Box S2 Ultra Black

The Pro-Ject Stream Box S2 Ultra sits at the top of Pro-Ject's compact S2 Box Series, designed to bring audiophile-grade network streaming to any existing hi-fi system. Rather than replacing your current DAC or amplifier, the Stream Box S2 Ultra acts as a high-performance network bridge: it connects to your home network via Ethernet or Wi-Fi and delivers bit-perfect audio to any USB DAC through its dedicated, audio-optimised USB-A output. Whether you are breathing new life into a classic DAC or building a compact, all-digital source stack, the Stream Box S2 Ultra provides modern streaming capability without compromise.

Network Bridge and USB Detox

At its core, the Stream Box S2 Ultra functions as a network bridge, bypassing audio files directly to your DAC without re-encoding or altering the bitstream. Because many premium DACs accept only a single USB input, Pro-Ject has also equipped the unit with a Micro USB-B PC input: connect a computer here and the Stream Box S2 Ultra acts as a USB detox device, cleaning the noisy USB signal from a laptop or desktop before passing it to the DAC. The dedicated internal power supply for the USB-A output is built to audiophile standards, isolating the digital audio path from system noise.

Streaming and Connectivity

The Stream Box S2 Ultra supports an impressive range of streaming services: Spotify, TIDAL, Qobuz, and HighResAudio (HRA) Streaming. TuneIn Internet Radio is also built in, providing access to stations worldwide. For local playback, two USB-A inputs (one front, one rear) accept external hard drives, supporting file formats up to PCM 32bit/352.8kHz and DSD256. Multi-room operation supports up to six simultaneous devices.

Roon Ready certification means the unit appears natively in Roon's interface as a zone endpoint, enabling bit-perfect playback across a Roon system. AirPlay-style streaming is supported via Shairport, allowing Apple device users to send audio directly to the unit. Audirvana is also compatible. Bluetooth Classic with aptX and Bluetooth Low Energy round out the wireless options.

Network connectivity covers both wired Gigabit Ethernet and 802.11 b/g/n Wi-Fi. The rear panel also includes an HDMI output for connecting a monitor to display the graphical user interface. Control is possible via a dedicated iOS/Android app, any standard web browser, or through Roon.

CD Ripping

An often-overlooked capability is built-in CD ripping: connect an external USB CD drive to either USB-A input and the Stream Box S2 Ultra can rip your CD collection directly to an attached hard drive, making it a convenient tool for digitising physical media without a dedicated computer.

Design and Build

The Stream Box S2 Ultra shares the compact 105 x 37 x 105mm footprint common to the S2 Box Series, making it easy to integrate into a rack or stack alongside other Pro-Ject components. The Black finish is a matte powder-coated chassis that complements both modern and classic hi-fi equipment. At just 375g (excluding the external power supply), it is genuinely compact. The unit has been awarded the EISA Best Product award, recognising its value and breadth of capability within its class.