The 851D is an affordable, well–made DAC/digital preamp that would please most serious music listeners.

Cambridge Audio Azur 851D DAC Review


Cambridge Audio Azur 851D DAC

  • Upsampling to 24-bit/384kHz
  • Balanced XLR and Unbalanced audio outputs
  • Digital Filtering
  • Headphone output
  • Bluetooth Connectivity

The Digital / Analogue Converter seems to have managed to become one of the most significant pieces of audio gear in most systems, and if they can double as a preamplifier, the more signifi-cant it has become. It seems we’ve come around; what used to be a simple setup of components, turntable, 2-channel integrated and speakers became a rack of preamp, turntable, phono stage, amplifier, CD player and speakers. Ironically, has digital reverted us back to the trio of DAC, amplifier and speakers, with sources being digital.

DAC Upsampling:

Dual Analog Devices AD1955 24-bit DACs. Analog Devices Black Fin ADSP-BF532 32-bit DSP performing 2nd Generation ATF2 upsampling to 24-bit/384kHz.

Filters Digital Inputs:

Linear phase, minimum phase or steep modes. S/PDIF, TosLink optical, BNC, AES/EBU, BT100 BluetoothUSB audio input


Type B conforming to Audio profile 1.0 or USB Audio profile 2.0 (user selectable) 1.0 or USB Audio profile 2.0 (user selectable)

Analog Audio Outputs:

Balanced XLR and unbalanced RCA analog audio outputs.

Sample Rates Supported:

USB Audio 1.0 16-24 bit, 32-96kHz, USB Audio 2.0 16-24 bit, 32-192kHz, TosLink 16-24 bit, 32-96kHz, S/PDIF 16-24 bit, 32-192kHz, BNC 16-24 bit, 32-192kHz, AES/EBU 16-24 bit, 32-192kHz, BT100 Bluetooth receiver: A2DP plus aptX

Maximum power Consumption:



4.5” H x 16.9” W x 14.7″ D






Cambridge Audio


Cambridge Azur, Cambridge, DAC, Cambridge Azur 851D D/A, Converter, Secrets DAC reviews

Design and Setup

Cambridge Audio Azur 851D DAC Review

The Cambridge Azur 851D is part of a threesome of “flagship” status that includes the 851A preamplifier and the 851W amplifier. The design for all three is non-assuming and quite conven-tional in appearance. Available in both black and silver, they possess a sturdy old-world solidity and heft. Although I have all three from Cambridge, I really wanted to concentrate on the DAC but having said that, the combination is killer, I love all three pieces on their own merits.

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Stylistically what is common to all three is the centered LCD display and in the case for the 851D, like any preamplifier, it shows the input selected and a larger volume display and is used for the pre-amp setup. It is used for besides volume, balance control, bass and treble. Each input can be manually selected via an adjacent touch button. The input selections can be renamed to make them easier to select. A filter and phase selection can be assigned to each input.

The Cambridge Azur 851D is part of a threesome of “flagship” status that includes the 851A preamplifier and the 851W amplifier. The design for all three is non-assuming and quite conven-tional in appearance.

Cambridge Audio Azur 851D DAC Review

The pre-amp setup allows for bass management with either a flat response or a 200Hz low pass filter can be applied.

The volume control dominates the right side and is smooth and silky to turn. To the left of the display (which has a nice shiny glimmer framing the display) is the standby on/off, a headphone jack, a setup menu button and a digital filter display, more on that later.

Before I get to the back of the component, the top sports symmetrical vents on each side and the engineers placed them to allow stacking of the other 851 units.

The back features a hard on/off button and detachable power cord. But more importantly, 6 digi-tal inputs that include Toslink, PDFI and BNC coaxial, and an AES/EBU Balanced input. Two of the inputs require you to choose either the PDIF or Toslink. All inputs will give you 16-24 bit up to 96 kHz sampling but you will need to use one of the others besides the Toslink to get the best possible sampling up to 192 kHz.

The back also has several other connections; an asynchronous USB B type socket to connect your computer, an RS232C and IR emitter in for the custom installer, a trigger out and control Bus in and out for commands to other units. Finally a Bluetooth Adaptor port, the BT100 allows you to use it with any Bluetooth device wirelessly and if you simply want to charge your device.

Outputs are from either conventional RCA unbalanced or from XLR balanced sockets.

Cambridge Audio Azur 851D DAC Review

If you literally do not use analog sources, the 851D can be the only preamp you need. An active digital preamplifier, meaning it can be used without a preamp all together, directly into a power amplifier. But it must be setup.

The 851D is fitted with two D/A converters in the AD1955 24 bit DAC’s used in a dual differen-tial mode. Because the D to A conversion is noisy, The DSP in the 851D include three filter functions; Linear, Minimum and Steep Phase. The Linear phase filter delays the signal of the en-tire frequency range to time align the signal at the output. The downside is potentially a more harsh sound. The Minimum Phase although does not group delay the signal, it exhibits less of the potential pre-ringing associated with impulse spiking from the Linear filter but you may give up some accuracy or coherence. The Steep or low-pass filter is similar to the Linear filter but a trade-off of more ringing but “optimized for stop band attenuation of close-in aliasing images”. The example given is the steeper filter attenuates aliasing at 22 kHz by 80dB for conventional CD quality material, say 44.1 kHz.

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The Cambridge 851D is also fitted with adaptive time filtering that up-samples all signals to 24-bit-386kHz and thereby reducing digital jitter via a 32-bit DSP “2nd Generation ATF2” proces-sor.

Cambridge Audio Azur 851D DAC Review

In conjunction with the 851D I used the Cambridge Azur 851W amplifier as well for an excep-tional combination. I fed it obviously only digital sources mostly from my Mac Book Pro but also fed it a digital signal from my Marantz 11S2 SACD player. I used a Transparent Audio USB cable. Speakers were the amazing GoldenEar Triton One.

Cambridge Audio Azur 851D DAC Review

There are many features that are subtle that should be mentioned. Adjusting the volume display to use “-90dB-0” as a reference or going from 0-90 depending on your taste I suppose. Volume also drops during standby mode and increases once out. There is also a control menu for custom installers which is beyond this review.

Cambridge Audio Azur 851D DAC Review

I must also mention the remote control of course. It is surprisingly thorough in features including a dimmer for the backlight display and an unconventional headphone volume control and trigger control. But it includes all the setup features and navigation buttons along with the conventional input selection, filter and phase mode selection. It also allows skip, pause and play features for playlist and tracks along with volume and mute control.

In Use

One glitch I came across was while playback of USB from my Mac Book Pro, raising the vol-ume too quickly dumps the signal and only re-booting – turning the 851D off and on again re-connected it to my laptop. It only occurred by raising the volume too quickly, not if I did it grad-ually. It also places your volume back at a preset -40dB. I cannot tell you whether this was a Mac issue alone or both but it happened once and didn’t happen again so I ignored it and went on. That’s digital, live with the glitches.

One of the things about playing mostly digital files is how much you speed through material, I went through a ton listening on the 851D and as everyone is aware, digital music quality is all over the place, we still haven’t defined what Hi-Res is, technically, yet. Anything better than CD quality is the best I can tell. What’s my point? The 851D managed to offer the best of each track regardless of playback quality.

Soundstage through the GoldenEar Triton One speakers was wide and deep. I did find voices to be a bit forward, but I have found that is the nature of digital audio. Cassandra Wilson’s Glam-oured album is nicely recorded, her presentation places her just slightly forward of the band, but her voice is rich and sultry. Speaking of deep, bass was clean and extended. Diana Krall’s Girl in The Other Room (I must have a thing for Chick singers) is also sultry but my favorite track Temptation features a wonderful standup bass that rings with deep tones, and the 851D captures that cleanly, with plenty of detail. Playing I did enjoy mostly acoustic material that offered not surprisingly, amply warm playback. David Russel’s Aire Latino is a wonderful medley of classic guitar pieces that aren’t necessarily intimate in their recording yet the 851D gives the solo guitar a sense of strength, distinguishing each pluck and finger slide.

The Cambridge pair ultimately sounded very good, I honestly was expecting dry, harsh or simply flat sounding music. But I heard none of that. There was excellent depth and breadth to the mu-sic. Paired with the 851W it was never lacking in strength and dynamics, even at lower volumes.

Cambridge Audio Azur 851D DAC Review

Playing with the filter selections, my personal preference was in Linear mode for its’ cleaner dy-namic, yet each of the other two also seem to offer their own benefits. The 851D will allow dif-ferent source inputs to have their own option of filter, remembering where you left/set it. Alt-hough each has trade-offs, I found the initial Linear setting to be best for me. I think this feature is best experimented with your system and the results you get, specifically the speakers.


Cambridge Audio Azur 851D DAC Review

I truly hate the term “value”. I’m not entirely sure how it applies, isn’t it all relative anyway? In the audio world, $1,500 is a modest price to pay for a world class DAC I suppose, but to most out there it’s a lot of money. But anyone who wants to take on digital music seriously, the 851D is so feature packed and flexible, it’s hard not to consider and there is a whole lot to love. The Bluetooth option alone places it heads above the crowd.

I was beyond pleasantly surprised, Cambridge designed and engineered a serious product that most audiophiles would love to own. They just have to remove their CD players and turntables from their racks to make room for it.