Streamers — Arcam ST25

The ST25 is the top network streamer of Arcam's Radia series, designed in Cambridge, UK, on a new streaming platform with a new user interface and companion app. It is a dedicated streaming source with its own DAC and analogue outputs, and Arcam designed it as the natural partner for the Radia A25 integrated amplifier, although it works with any hi-fi system.

Key specs that matter

The ST25 plays PCM at up to 32-bit/384kHz and DSD256, using a DAC from ESS's HyperStream IV family in a balanced configuration. Streaming covers Apple AirPlay 2, Google Cast, Spotify Connect, TIDAL Connect, Qobuz Connect, UPnP, internet radio and podcasts, and the unit is Roon Ready. Supported formats include FLAC, WAV, AIFF, ALAC, AAC, MP3, OGG, WMA and DSD. Network connection is by dual-band Wi-Fi or Ethernet, and a USB-A socket plays music from storage devices. Outputs are analogue RCA plus coaxial and optical digital outputs. The front panel has a bonded 6.5-inch high-resolution display. The chassis measures 432 x 99 x 329mm and weighs 5kg.

Engineering and use context

The digital audio and streaming platform sits on a six-layer circuit board with a ground plane running through the entire board, keeping noise and interference from the network and processing sections away from the sensitive conversion and analogue stages. The ESS DAC runs in a balanced configuration with jitter elimination. Arcam uses two power supplies - a linear supply built around a toroidal transformer drives the whole unit during playback with lower noise than a switching supply, while a switch-mode supply operates only in standby for efficiency. The bonded display, with no air gap between glass and panel, keeps album artwork legible from across the room. Setup and control run through the Arcam Radia app, which also manages presets, internet radio and podcasts, and a control link lets a Radia amplifier and the ST25 operate as a single system from a phone or tablet. The coaxial and optical outputs allow the ST25 to act purely as a network transport feeding an external DAC. It ships in plastic-free packaging.

Pairing

Through its RCA outputs, the ST25 connects to any integrated amplifier or preamplifier, and with the Radia A25 it forms a two-box system controlled from one app. Owners with a preferred external DAC can use its digital outputs and bypass the internal converter.

Alternatives

Arcam's own ST5 is the smaller, less expensive Radia streamer designed to pair with the A5 and A15 amplifiers.