Audio T Verdict
The Cyrus 40 ST combines the convenience of BluOS streaming with the detailed and involving presentation expected from a dedicated Cyrus source component.
Its ESS Sabre DAC, analogue and digital outputs, digital inputs and USB storage playback give it considerably more flexibility than a simple network transport. The large colour display also makes it easier to live with than Cyrus streamers that rely almost entirely on app control.
Add the optional 40 PSU and the 40 ST becomes an even more ambitious digital source. It is a natural partner for the Cyrus 40 AMP, but its comprehensive output options allow it to work within a wide range of Hi-Fi systems.
Cyrus 40 ST Network Streaming DAC
The Cyrus 40 ST is a compact high-resolution network streamer with BluOS, an ESS Sabre ES9039Q2M DAC, analogue outputs, digital inputs and digital outputs.
It can connect directly to a conventional integrated amplifier or preamplifier using its analogue outputs, or operate as a network transport with a separate DAC or digitally equipped amplifier.
An optical and coaxial digital input also allow compatible external products to use the Cyrus DAC, while a rear USB-A socket provides playback from suitable USB storage devices.
Use the Internal DAC
- Connect the analogue outputs to an amplifier
- Uses the ESS Sabre ES9039Q2M DAC
- No separate DAC is required
- Two line-level analogue outputs are provided
Use an External DAC
- Connect through optical or coaxial digital output
- Compatible with suitable DACs and digital amplifiers
- Allows future digital-converter upgrades
- Only one digital output connection is required
BluOS High-Resolution Streaming
BluOS provides the principal music-streaming platform and everyday control system for the 40 ST.
The BluOS Controller app provides access to supported music services, internet radio, podcasts, compatible network libraries and music stored on connected USB devices.
The app is available for compatible iOS, Android, Kindle, Mac and Windows devices, allowing music to be selected and controlled from a phone, tablet or computer.
Network playback is supported at resolutions up to 24-bit/192kHz, subject to the source material, selected service and subscription.
ESS Sabre ES9039Q2M DAC
Digital-to-analogue conversion is handled by an ESS Sabre ES9039Q2M 32-bit DAC using HyperStream IV Dual DAC technology.
Cyrus has optimised the surrounding components, circuit-board layout and power arrangements rather than relying solely on the specification of the DAC chip.
The manufacturer states support for PCM up to 24-bit/192kHz and DSD256, while BluOS network playback is specified at up to 24-bit/192kHz.
Two Analogue Line Outputs
Two stereo line-level analogue outputs allow the 40 ST to connect directly to an integrated amplifier or preamplifier.
This connection uses the streamer’s internal ESS Sabre DAC, making the 40 ST a complete digital source rather than a transport-only product.
The outputs are described by Cyrus as line-level outputs rather than variable preamplifier outputs. Listening volume should therefore be controlled by the connected integrated amplifier or preamplifier.
Optical and Coaxial Digital Outputs
An optical TOSLink output and coaxial RCA output allow the 40 ST to send its digital signal to a compatible external DAC or amplifier.
This provides the freedom to compare the Cyrus DAC with another converter or to retain the streaming section while upgrading the digital-to-analogue conversion at a later date.
Coaxial connections require a suitable 75-ohm digital cable, while an optical connection provides electrical isolation between the two components.
Optical and Coaxial Digital Inputs
Unlike the Cyrus Classic STREAM, the 40 ST includes one optical and one coaxial digital input.
These allow compatible external sources such as a CD transport, television, games console or another digital player to use the 40 ST’s ESS Sabre DAC and analogue output stage.
The external source must be configured to provide a compatible stereo digital signal. A television may need to be set to PCM rather than a multichannel surround format.
USB Music Playback
The rear USB-A socket accepts compatible USB memory sticks and storage drives containing supported music files.
Once connected, the stored music can be browsed and selected through the BluOS Controller app.
This is not an asynchronous USB-B computer-audio input. A computer normally connects to the 40 ST through the home network rather than by a direct USB audio cable.
Wired and Wireless Networking
Built-in dual-band Wi-Fi 5 supports compatible 2.4GHz and 5GHz wireless networks.
A Gigabit Ethernet connection is also provided for a wired network installation. A wired connection can be useful where the equipment rack is close to the router or a network switch.
Reliable streaming depends on the quality and coverage of the home network, particularly when playing high-resolution music or using several network players at the same time.
Roon Ready
The Cyrus 40 ST is Roon Ready and can operate as a network endpoint within a compatible Roon system.
Roon can combine locally stored music and supported streaming services within one organised library, with music delivered to the 40 ST over Ethernet or Wi-Fi.
Roon software and any associated subscription are supplied separately.
Apple AirPlay 2
AirPlay 2 allows compatible Apple devices and applications to send audio to the 40 ST across the home network.
The streamer can also be grouped with other compatible AirPlay 2 products for synchronised playback in more than one room.
MQA Decoding
MQA decoding and rendering are included for compatible MQA files and streams.
MQA support is separate from conventional high-resolution FLAC, WAV and other lossless formats, which can also be played through suitable BluOS sources.
Five-Inch Colour Display
A five-inch high-resolution colour TFT display shows source, track, album and playback information on the front panel.
Hidden-until-lit capacitive controls provide access to commonly used functions while preserving the clean appearance of the toughened-glass fascia.
The supplied Cyrus remote provides additional control, although music browsing and streaming-service selection are primarily handled through the BluOS app.
Optional Cyrus 40 PSU Upgrade
The
Cyrus 40 PSU
connects to the streamer through its dedicated rear multi-pin socket.
When connected, the external supply powers the analogue side of the DAC and the BluOS network module, providing those sections with separate, clean and stable power.
Both the 40 ST and 40 PSU remain connected to mains power, and the two components communicate automatically to configure the external supply.
The 40 ST is not compatible with the older PSX-R2 or the PSU-XR.
40 ST or Classic STREAM?
The
Cyrus Classic STREAM
also uses BluOS but features the earlier Classic casework, an ESS ES9038Q2M DAC and PSX-R2 upgrade compatibility.
The 40 ST adds the newer ES9039Q2M DAC, a five-inch colour display, optical and coaxial digital inputs and compatibility with the Cyrus 40 PSU.
The Classic STREAM remains a natural choice for an existing Classic Series system, while the 40 ST provides the more advanced feature set and matches current 40 Series components.
No Amplifier or HDMI eARC
The 40 ST does not contain a loudspeaker power amplifier and cannot drive passive speakers directly.
It also does not include HDMI eARC. A compatible television can instead use the optical or coaxial digital input, with volume controlled by the connected amplifier.
Installation and Network Setup
Position the streamer on a rigid, level and ventilated Hi-Fi shelf with enough space behind it for audio, network and 40 PSU connections.
For wireless use, avoid enclosing the streamer inside metal furniture or placing it where Wi-Fi coverage is weak.
Switch off the connected amplifier before changing analogue or digital connections, and avoid routing low-level analogue cables tightly alongside mains leads.
Key Features
- BluOS high-resolution streaming platform
- Network playback up to 24-bit/192kHz
- ESS Sabre ES9039Q2M 32-bit DAC
- HyperStream IV Dual DAC technology
- Two line-level analogue outputs
- One optical digital output
- One coaxial digital output
- One optical digital input
- One coaxial digital input
- USB-A storage-device playback
- Gigabit Ethernet connection
- Dual-band Wi-Fi 5
- Apple AirPlay 2
- Roon Ready
- MQA decoding and rendering
- Five-inch high-resolution colour display
- Hidden-until-lit touch controls
- Remote control included
- Cyrus 40 PSU compatible
- Five-year manufacturer warranty
Frequently Asked Questions
Does the Cyrus 40 ST contain a DAC?
Yes. Its ESS Sabre ES9039Q2M DAC provides line-level analogue outputs for connection to an integrated amplifier or preamplifier.
Can it be used with an external DAC?
Yes. Optical and coaxial digital outputs allow it to operate as a network transport with a compatible external DAC.
Can I connect a CD transport or television?
Yes. One optical and one coaxial digital input are provided. A television may need to be configured for stereo PCM output.
Does it have HDMI eARC?
No. A compatible television can instead connect through the optical or coaxial digital input.
Can it play music from a USB drive?
Yes. Compatible storage devices can connect to the USB-A socket and be browsed through the BluOS app.
Can I connect a computer directly by USB?
No. The 40 ST does not provide a USB-B computer-audio input. A computer can access and control it through the network.
Does it support wired networking?
Yes. Gigabit Ethernet is provided alongside dual-band Wi-Fi 5.
Can it drive passive speakers directly?
No. It requires an integrated amplifier, pre and power amplifier combination, or another suitable amplified system.
Which Cyrus power supply is compatible?
The 40 ST is compatible with the Cyrus 40 PSU. It is not compatible with the Classic PSX-R2 or PSU-XR.
Why Buy From Audio T?
- Experienced Cyrus and network-audio specialists
- In-store demonstrations through participating branches
- BluOS and home-network setup guidance
- Help choosing between analogue and digital outputs
- Amplifier and external DAC matching advice
- 40 PSU upgrade demonstrations and support
- Ethernet, optical, coaxial and analogue cable guidance
- Ongoing system setup and technical support
Contact your local Audio T store
to arrange a demonstration or discuss adding the Cyrus 40 ST to your Hi-Fi system.