Streamers — Pro-Ject Stream Box S2

The Stream Box S2 is a pocket-sized multiroom streamer with integrated digital to analogue conversion, made by the Austrian brand Pro-Ject Audio Systems. The company developed it as a partner for its small amplifiers such as the MaiA S2 and Stereo Box S2, matching their case style. The MSRP at launch was EUR 299 including VAT, and the UK price was GBP 269.

Key specs that matter

An ESS9023 converter chip does the decoding, and playback reaches 24 bit and 192 kHz in MP3, FLAC, WAV, ALAC, APE and AAC files. Spotify and TIDAL are built in, with Qobuz and Amazon Music also listed, and internet radio comes through TuneIn and iHeartRadio. UPnP and DLNA handle network libraries, and AirPlay is supported. The unit joins a network by Ethernet or by 802.11 b/g/n WiFi with a supplied antenna. Outputs comprise a fixed-level RCA pair, a variable 3.5 mm jack and an optical S/PDIF socket. A USB A port on the front reads flash drives and hard disks, and a 3.5 mm line input sits at the back. The metal case is 103 x 37 x 122 mm and weighs 375 g, and power arrives as 5 V DC through a micro-USB socket.

Engineering and use context

Pro-Ject argues that many rival streamers focus on the app while fitting a basic DAC and output stage in a plastic box, so this model got a solid metal enclosure that screens against interference. Multiroom groups may contain up to 10 units over Ethernet or 6 over WiFi, and the maker limits the zone count so that the shared stream stays at CD resolution of 16 bit and 44.1 kHz instead of being reduced to MP3 quality. Two units can also form a stereo pair, each playing only the left or right channel. Grouping is done in the free Pro-Ject Stream S2 app for iOS and Android by dragging one device onto another, and volume can be shared or set per room. Setup runs through the app or a web page reached via the unit's own hotspot, and a WPS button on the rear clears the network settings. A front Local button switches to the line input, and a sleep timer can send the player to standby.

Pairing

The fixed RCA output is meant for a preamplifier or integrated amplifier, while the adjustable headphone-size jack can feed a power amp or powered monitors without a preamplifier with volume set in the app. Placed next to a pair of powered speakers, a unit turns them into a wireless system, and the optical output passes the digital stream on to an external DAC for owners who prefer a separate converter.

Alternatives

The Pro-Ject Stream Box S2 Ultra is a network bridge without its own DAC that feeds an external converter over USB at up to 32 bit and 352.8 kHz or DSD256, with Roon Ready certification.