Azur 851A

Integrated Class XD Amplifier


The 851 possesses incredible power, finesse and astonishingly low distortion. In its design we assessed every component for sonic excellence and revised, reviewed and optimised the signal path for minimal distortion. Thousands of hours were spent testing and tweaking, the result is an amplifier we’re incredibly proud of.

"A muscular amp that grips the speakers and serves up tight, powerful and extended bass.... cutting-edge technology for substantially less than high-end prices."

- European Imaging & Sound Association, August 2012


    Nothing prepares you for the sound quality of our 851A. Rated at 120 Watts per channel and built with a fastidious attention to detail, it presents your music with astounding depth and incredible clarity. The precision volume control provides remarkable stereo separation, while the overall effect is to give your music collection a new lease of life.


    We built the 851A without sonic compromise, and that’s true of the connectivity too. Nine RCA inputs cater for regular analogue inputs, while for high end components there are two sets of balanced XLR inputs. We’ve added a pre-out for connecting to a subwoofer or power amp, while two sets of speaker terminals allow for bi-wiring or running additional speakers in a second location. Finally, Control Bus inputs allow the linking of compatible Cambridge Audio products for easy control from one remote.


    Rather than use Class A or Class AB amplifier designs, we developed a novel and unique new design called Class XD, which combines the sonic purity of Class A and the efficiency of Class AB for the best possible result. For more info on this patented technology click here.

    The primary toroidal transformer provides unrestricted power to the dual mono amplification blocks. It’s a true audiophile transformer that will operate without distortion and with no buzz, interference or hum. While a second, smaller toroidal transformer takes care of pre-amplification processes. For more information on toroidal transformers and why we use them view the videos below.

  • Press reviews

    • Witchdoctor

      New Zealand, January 2013

      PRODUCT OF THE YEAR "They seem to be the absolute class leaders at their respective price points. The build quality that just shouldn’t be possible for the money, and the huge feature sets are impressive enough, but with sound quality that is out of all proportion to their price tags, these components are on another level when it comes to value for money."
    • Stereophile

      United States, January 2015

      "To this audiophile, the azur 851A represents a versatile and extraordinarily musical cornerstone on which to a build a truly enjoyable high-end system that can play all types of music with righteous aplomb for little cost"
    • Music Emotion

      Netherlands, December 2012

      "The Cambridge Audio engineers succeeded in the difficult task to improve the 840-models. Especially used in combination they form an impressive and balanced set-up. An A-grade result! Wonderful products at a very good price."
    • HD Fever

      France, October 2012

      "Musical, dynamic, pleasurable and sophisticated listening, enormous power, impeccable build quality, great design and ease of use - who could ask for more?"
    • European Imaging and Sound Association

      Portugal, August 2012

      "So while the 851C DAC/player brings a quiet composure to the party, the 851A is a wolf in sheep’s clothing, a muscular amp that grips the speakers and serves up tight, powerful and extended bass. In the 851C and 851A you’re getting cutting-edge technology for substantially less than high-end prices. Add the best speakers you can afford and this two-channel system will deliver a taste of hi-fi heaven."
    • Hi-Fi News

      United Kingdom, August 2012

      "Frankly, the feature set of the 851C and 851A is the stuff of high-end audio dreams, but packaged in sensibly-priced components... As is so often the case with products from Cambridge Audio, what you're getting is cutting-edge technology for substantially less than high-end prices... This Azur combo took me to places I haven't been for a long time!"
    • Hi-Fi Choice

      United Kingdom, June 2012

      "They now compete with the very best in class when it comes to sound and are pretty much in a league of their own when it comes to features... This refined and revealing pair delivers a dynamic, clean and engaging result."

      Customer Reviews

    • The details

      Power output 120W RMS into 8 Ohms 200W RMS into 4 Ohms
      THD (unweighted) < 0.001% 1 kHz at 80% of rated power 0.01% 20 Hz - 20 kHz at 80% of rated power
      Audio inputs 2 x balanced XLR, 8 x RCA inputs
      Audio outputs Preamp output Record output
      Frequency response 10 Hz - 50 kHz +/- 1 dB
      S/N ratio (ref 1w) > 93 dB (ref 1W/8 Ohm)
      Input impedance Inputs 1 and 2 (balanced) 20 kOhm, Inputs 1-7 unbalanced 20 kOhm Rec Input 20 kOhm
      Power amp damping factor > 110 at 1 kHz
      Max. power consumption 800W
      Min. power consumption Active (no signal) 70W
      Standby power consumption Standby <0.5W
      Tone control Shelving type Max bass boost/cut +/- 10 dB at 10 Hz Max treble boost/cut +/- 7.5 dB at 20 kHz
      Colour Silver or black
      Dimensions (WxHxD) 430 x 115 x 385mm (16.9 x 4.5 x 15.2”)
      Weight 15.0Kg (33lbs)
      In the box Azur 851A Integrated Amplifier, Power Cable, 3 x AAA Batteries, Remote Control