Cyrus 40 ST

The Cyrus 40 ST is a high-resolution network player that blends elegance with sonic precision. Powered by the BluOS platform, it offers streaming up to 24-bit / 192 kHz with smooth, natural playback. Built into the iconic aluminum chassis of the 40 Series, it integrates seamlessly with any modern hi-fi system thanks to its Roon Ready and AirPlay 2 compatibility.

A design that breaks with three decades of tradition

For the first time since the 1990s, Cyrus is moving away from its historic die-cast magnesium chassis. The 40 ST adopts a fully re-engineered machined aluminum enclosure, slightly larger (88 × 220 × 385 mm) than its predecessors, providing optimized internal volume for better circuit layout.

The tempered glass front conceals a perfectly legible 5-inch color TFT display, five capacitive touch buttons invisible when idle, and the Cyrus logo serving as the power switch. A rotary encoder encircled by an LED ring controls the volume with impeccable mechanical precision. The beveled edges visually lighten the whole, striking a balance between physical presence and discretion in a brushed black anodized finish.

Custom-tuned digital-to-analog conversion

Cyrus deploys a custom implementation of the ESS Sabre ES9039Q2M converter with HyperStream IV technology in a dual-DAC configuration. The chip is theoretically capable of handling up to 32-bit/768 kHz and DSD1024, but BluOS deliberately limits it to 24-bit/192 kHz—a choice that favors stability and ease of use.

The engineering team optimized every aspect of the PCB, from trace design to peripheral components. The analog output stages, improved over the Stream XR, benefit from a separate power supply that ensures an exceptionally low noise floor. Eight digital filters allow subtle tuning of the sound, with the Minimum Phase or Linear Phase in Slow Roll-Off options delivering the most natural rendering.

BluOS: the platform bringing audiophile streaming to the mainstream

Adopting BluOS, a proven platform from Lenbrook Media Group, allows Cyrus to focus on optimizing the audio circuitry. The BluOS Controller app (iOS, Android, Kindle, macOS, Windows) provides an intuitive interface with setup in just minutes.

The platform natively integrates over twenty streaming services (Qobuz, TIDAL, Spotify Connect, Amazon Music HD, Deezer) and thousands of internet radio stations. Compatible with Roon Ready out of the box and AirPlay 2 for Apple devices with Siri control, it enables up to 64 zones in multiroom. Transmission preserves signal integrity up to 24-bit/192 kHz without latency or compression on a properly provisioned network.

Connectivity designed for system integration

The rear panel reveals a minimalist yet thoughtful approach: two pairs of RCA analog outputs, coaxial and optical digital outputs, and digital inputs limited to one coaxial and one optical. This apparent frugality reflects Cyrus’s philosophy in which the 40 AMP amplifier centralizes multiple connections.

A USB-A port allows playback from external drives, while networking relies on Gigabit Ethernet and dual-band Wi‑Fi 5 (802.11ac) for maximum flexibility.

A sonic signature that transcends technical limitations

Despite its 192 kHz cap, the 40 ST extracts a remarkable amount of musical information. The soundstage impresses with its stability and meticulous organization, each instrument occupying a defined space within a convincing three-dimensional image.

The bass is authoritative and extended, a clear departure from the lightness of earlier Cyrus generations. The slightly forward midrange places vocals with palpable presence, revealing micro-inflections and vocal textures. The treble combines extension, finesse, and sweetness without harshness.

Dynamics are a major strength: both micro and macro contrasts are rendered with liveliness, with incisive attacks and natural decays that create a captivating, organic sense of breathing.

The 40 PSU upgrade: a substantial evolution

The external 40 PSU power supply, equipped with its own microprocessor, communicates with the 40 ST to optimize power distribution. The digitally controlled output voltages achieve remarkable stability.

Its addition significantly transforms performance: a wider soundstage, more natural micro-details, and improved instrumental separation. The most striking benefits concern bass resolution and the overall sense of authority in the presentation.

Technical specifications

Digital-to-analog conversion

• Converter: ESS Sabre ES9039Q2M 32-bit, HyperStream IV Dual DAC technology
• Maximum resolution: 24-bit / 192 kHz
• Architecture optimized for ultra-low noise and distortion
• Analog stages designed for maximum transparency

Connectivity

• Analog outputs
  • 2 × line level (RCA)
• Digital outputs
  • 1 × coaxial (S/PDIF)
  • 1 × optical (TosLink)
• Digital inputs
  • 1 × coaxial (S/PDIF)
  • 1 × optical (TosLink)
• USB-A port: file playback from external storage
• Network
  • RJ45 Ethernet (GigE 1 Gbps)
  • Wi‑Fi 5 (802.11ac, 2.4 / 5 GHz)

Compatibility and features

• Platform: BluOS (multiroom, high resolution, intuitive control via dedicated app)
• Supported services: high-resolution streaming, internet radio, local network playback
• Roon Ready and AirPlay 2
• Compatible with the 40 PSU power supply for optimized external power

Build and design

• Series 40 aluminum chassis, precision machined
• Compact, elegant design with premium finish
• Dimensions (H × W × D): 88 × 220 × 385 mm
• Weight: 4.8 kg