Featuring 24-bit/384 kHz Audio Upsampling
The Azur 851D is Cambridge Audio's flagship DAC and digital preamplifier in one powerful hub. You can play your music back from just about anywhere – from home networks, hard drives, and computers, to online streaming services such as Spotify, Pandora, and even YouTube. However, reproducing this digital music as the original artist intended is a complex challenge. For example, a laptop is designed to be a laptop, not a piece of hi-fi gear, so sound quality is usually compromised as a result.
The 851D is for audiophiles who want to store and play their music digitally, but with no compromise on sound quality. By connecting all of your digital audio sources to the 851D, you bypass the inferior internal DACs found in the digital source device, such as a PC or laptop. The 851D then performs the critical digital-to-analog conversion in far higher quality than the source device ever could, and then it sends this higher quality analog music signal to your amplifier.
"I was immediately impressed," reports reviewer jt25741 in a Head-Fi.org post for February 12, 2014. Listening to the headphone output with a pair of AKG K550s "produced very clean, detailed and harmonically rich sounds."
It's a Digital Preamp, Too!
The 851D can also be used as a digital preamplifier. When the optional preamplifier mode is enabled, the 851D features a high quality volume control, allowing you to connect directly to a power amplifier such the Azur 851W, without the need to first connect to a traditional analog preamplifier.
By using digital preamplifier circuitry, the 851D's audio signal remains in the digital domain for much longer, compared to a traditional analog integrated or preamplifier. Because the audio signal remains digital, and is only converted to analog at the very last minute, it is far less susceptible to analog signal deterioration. This means that the sound you hear is as close as possible to the original recording.
The Rolls Royce of DACs
The 851D features twin Analog Devices 1955 DACs (the Rolls Royce of DACs!) used in 'dual differential' mode for the very best digital to analog conversion. Each stereo channel processes information completely separately for greater accuracy, bringing you far closer to the original recording for a truly amazing experience.
The 851D features ATF2 (2nd generation Adaptive Time Filtering) audio upsampling. The ATF2 system intelligently upsamples all incoming audio to 24-bit/384kHz. ATF2 also dramatically reduces digital jitter, a form of audible interference which affects all digital music. Jitter is most apparent when music is stored on computer hard drives and is the audio equivalent to a blurred image in a movie. Data scrambling circuitry also maintains signal quality and purity during quieter periods by reducing background noise.
High Quality Asynchronous USB
The 851D includes a high quality asynchronous USB audio input for playback of up to 24-bit/192kHz high resolution files from a connected computer. An asynchronous USB audio input means that the 851D acts as a high quality external soundcard, allowing bit-perfect transfer from the connected computer to the 851D, ensuring all data is delivered in perfect timing for the highest possible sound quality.
Most computers can't play high resolution audio through their headphone output. Featuring asynchronous USB audio clocking, and supporting both USB Class 1 and USB Class 2, the 851D can be used to play everything from MP3s to the highest quality 24-bit/192kHz studio master recordings from your computer, all free from unwanted noise, jitter and distortion.
The 851D can be switched into USB Class 2 mode, allowing you to play everything from MP3 to the highest quality 24-bit/192kHz studio master recordings straight from your computer. When running in Class 2 mode, the 851D can also use Cambridge Audio's dedicated Windows USB Class 2 USB driver. This allows you to bypass the computer operating system's poor audio path, preventing unwanted interference and re-sampling, guaranteeing a professional quality audio output.
The 851D's six digital inputs include S/PDIF coaxial, Toslink optical, as well as BNC coaxial and AES/EBU. Plus there's asynchronous USB Audio and Bluetooth wireless connectivity, meaning that wherever your music comes from, you can play it back in stunning quality through the 851D. All inputs are upsampled to 24-bit/384kHz output. So you can connect a world of digital source components from set-top boxes to media streamers, smartphone docks to computers.
The 851D features both unbalanced RCA and balanced XLR audio outputs, as found in many modern high-end hi-fi separates such as our 851E and 851W pre and power amplifiers.
Premium Toroidal Power Transformer
The 851D boasts an audiophile grade toroidal transformer. Cambridge Audio was one of the first manufacturers to use toroidal transformers in the 1970s, and continues to use them today. Some of the benefits of a toroidal transformer, over the cheaper, inferior EI transformers used by most other manufacturers are high quality power output to the amplification circuits, with no clipping of the waveform signal, to provide a consistent signal, along with no transformer noise, buzz or hum.
Large power reserves allow the transformer to deliver high peaks of volume when required. The transformer is fully shielded against internal and external electrical interference to maintain quality of power and signal.
Maximize Streaming Services and Apps with Bluetooth
Bring the 851D's stunning, superior audio quality to all your apps and streaming services via your smartphone, tablet, or computer. Instantly and easily listen to popular services such as Last.fm or Spotify, played back in stunning quality through the 851D's Bluetooth connection.
This extra functionality allows you to browse and control the endless content these devices offer, from the comfort of your chair. In addition to the standard Bluetooth Codec, the 851D also supports the higher quality Bluetooth aptX, which is used by most portable devices now.
Digital Preamp, with Analog Power
Why not connect the 851D directly to the Azur 851W power amplifier, to create a truly astonishing digital music system? Or use it with any premium power amp for head-spinning performance.
Unlike many digital preamplifiers, the 851D's digital preamplifier is the highest possible quality thanks to the powerful 32-bit Blackfin DSP (Digital Signal Processor), which also drives the ATF audio upsampling system. Most digital preamplifiers use 'bit reduction' to adjust the level of the volume output, however this results in much lower sound quality because digital information is being cut out of the original audio signal.
Instead, the 851D digital preamplifier uses the Blackfin DSP to control the level of the volume output, meaning that the entire digital signal remains fully intact for the best possible sound.
All Metal Design
Electronics (and therefore sound quality) are particularly susceptible to vibration. That's why Cambridge Audio used a low resonance, acoustically-dampened metal chassis to eliminate as much vibration as possible. This ensures that the highest sound quality is extracted from each audio source.
For added convenience, all of the products from the new Azur 851 range can be operated from one ergonomically designed, easy-to-use remote control.
"I was immediately impressed by the apparent build-quality, packaging care, and overall feel of everything. It feels quite high-end."
"The head amp in the 851D produced very clean, detailed and harmonically rich sounds through the DAC/Pre."
- Reviewer jt25741, Head-Fi.org, February 12, 2014
Azur 851D Digital-to-Analogue Converter
Why are DACs so important?