Pro-Ject Stream Box E silver

After the Uni Box S3 launched in summer 2025, Pro-Ject continues rolling out its network playback ecosystem with the Stream Box E. This compact audio player is based on the WiiM OS platform, supports dual-band Wi-Fi and Bluetooth 5.0, includes a digital-to-analog converter, a preamplifier function with volume control, and an analog RCA input. All in a miniature format that fits into an existing hi-fi system without disrupting it.

An operating system shared with WiiM

The Stream Box E runs on WiiM OS, the same software platform used by WiiM network players. It is controlled via the Pro-Ject Home app (iOS and Android), which manages network setup, playback, equalization, and multiroom. Setup starts with automatic device detection in the app, followed by a Wi-Fi setup wizard. A long press on the play/pause button on the front panel resets the Wi-Fi connection without going back through the app.

The app provides access to a wide range of streaming services: TIDAL Connect, Spotify Connect, Qobuz, Amazon Music, Deezer, Napster, Pandora, TuneIn, SoundCloud, among others. Playback is supported up to 24-bit / 192 kHz. A graphic and parametric equalizer, configurable independently for each source (Wi-Fi, Bluetooth, analog input), allows playback to be adjusted to the listening environment or personal preferences.

Three configurations, one enclosure

The Stream Box E combines the functions of a network player and preamplifier, allowing it to adapt to several system topologies.

Connected to an integrated amplifier, it adds network playback to a traditional hi-fi system. This separation between the network source and amplification can extend the lifespan of an amplifier by relieving it of the digital section, which evolves faster than the analog section.

Paired with a power amplifier (such as the Amp Box S3 from the same range) and passive speakers, it works as a preamplifier with volume control, network playback, and an additional analog input for a turntable or CD player.

Connected directly to a pair of active speakers, it forms a minimalist listening system with access to streaming services and source switching. Volume can be controlled from the Stream Box E or from the speakers themselves.

Stream vinyl across the home network

The Pro-Ject True Wireless function sets the Stream Box E apart from most network players in this price range. The analog RCA input does more than just connect a wired source: it can also redistribute the signal to other compatible devices on the network, such as the Wireless Box E or the Uni Box S3. In practice, a turntable connected to the Stream Box E in the living room can be listened to in another room, on a second system, without cabling between the two.

Multiroom works both ways: the Stream Box E can send and receive audio wirelessly. Several devices from the new Pro-Ject generation (Stream Box E, Uni Box S3, Wireless Box E), as well as WiiM devices, can be grouped in the Pro-Ject Home app. Playback can be synchronized across all devices in the group or independent in each room.

Careful construction in a compact format

The chassis combines aluminum and metal, with electromagnetic shielding that protects the internal components from interference. Pro-Ject states that this protection allows the Stream Box E to be placed directly next to an amplifier, or even stacked on top of it, without degrading the audio signal. The aluminum front panel features three buttons (volume down, play/pause, volume up), also made of aluminum. Two finishes are available: black or silver. The external Wi-Fi antenna, screwed onto the rear, remains the only protruding element.

The power supply is external (5 V / 1000 mA DC), compatible with 100 to 240 V mains power. Operating consumption is specified at 200 mA DC, which is very low.

Connectivity and network: the essentials, nothing more

On the rear, there is a stereo RCA input, a stereo RCA output with gold-plated connectors, and an optical S/PDIF digital output (Toslink). The latter makes it possible to connect the Stream Box E to an external converter or to an audio system equipped with an optical input, for those who wish to bypass the built-in DAC.

Dual-band Wi-Fi (2.4 GHz and 5 GHz, 802.11 a/b/g/n/ac standard) provides the network connection. Bluetooth 5.0 is limited to SBC and AAC codecs: no aptX or LDAC, which restricts the quality of Bluetooth transmission from an Android smartphone. The absence of an Ethernet port is a deliberate choice for this compact format, but it deprives users of a wired connection, which is sometimes more stable in crowded Wi-Fi environments.

Pro-Ject does not specify the DAC chip model used. The stated measurements are solid for this segment: signal-to-noise ratio greater than 102 dB, channel separation greater than 106 dB at 10 kHz, total harmonic distortion less than 0.009%, and frequency response from 20 Hz to 20 kHz (-1.5 dB). The nominal output level is 3 Vrms.

Another point to note at launch: neither AirPlay 2 nor Roon Ready certification appears in Pro-Ject’s official documentation for this product. WiiM OS supports these protocols on some of its own devices, so a later update cannot be ruled out, but nothing is confirmed at this stage. Apple Music or Roon users will need to take this into account.

Technical specifications

Type and features

• Type: multiroom network streamer with preamplifier function
• Streaming technology: WiiM OS™
• Control app: Pro-Ject Home App
• Multiroom compatibility: yes
• Pro-Ject wireless streaming: audio transmission and reception over the network
• Network sharing function: broadcasting a connected analog source (e.g. turntable) to the multiroom system

Network and wireless connectivity

• Wi-Fi: dual-band 2.4 GHz / 5 GHz – 802.11 a / b / g / n / ac
• Bluetooth: version 5.0
• Supported Bluetooth codecs: SBC, AAC
• Compatible streaming services: TIDAL Connect, Spotify Connect, Qobuz and other streaming services
• Network compatibility: Uni Box S3, Wireless Box E and other new-generation Pro-Ject streamers

Connections

• Analog input: stereo RCA
• Analog output: gold-plated stereo RCA
• Digital output: optical S / PDIF Toslink

Audio performance

• Audio output level: 3 Vrms
• Frequency response: 20 Hz – 20 kHz (-1.5 dB)
• Channel separation: > 106 dB at 10 kHz
• Signal-to-noise ratio: > 102 dB
• Total harmonic distortion (THD): < 0.009 %

Construction and design

• Chassis: aluminum and metal with electromagnetic shielding
• Available finishes: black, silver

Power supply

• External power supply: 5 V / 1000 mA DC
• Compatible mains power supply: 100 – 240 V / 50-60 Hz
• Power consumption: 200 mA DC