Reviews of Attainable Hi-Fi & Home-Theater Equipment

Reviews of Attainable Hi-Fi & Home-Theater Equipment

I came late to the streaming game. Usually, I’ve got my old Apple MacBook Pro wired up to a dedicated external hard disk drive (where my music is stored) and whatever electronics I’m reviewing, and I run a long USB cable to my couch. Or I just keep getting up to change the song. It’s a pain in the ass, but my laziness knows no bounds. Sometimes I don’t eat dinner, just so I can avoid the hassle of having to make something and then clean up. The idea of forgoing the laptop entirely is pretty appealing, but . . . so much effort.

There’s something else: I think we’re at the point where I can confidently say that you’d have to go to considerable effort to find a digital-to-analog converter that isn’t, at the bare minimum, very good -- I keep asking myself why anyone would want or need to pay a penny over $2000 USD. I shake my head at the number of DACs that retail for $5000 or even $10,000 but make use of the same flagship Sabre ESS Reference chip found in, say, Benchmark Media Systems’ excellent DAC2 DX ($1895). I do think there’s merit in some of the boutique ladder DACs out there -- think MSB Technology -- but at this point, delta-sigma DACs are ubiquitous. Sussing out that final 1% or 2% of sound quality by using a pricey femtoclock to drive down jitter is all well and good -- better sound is always the goal here -- but at what price? Surely, digital has gotten to the point where the consumer’s cash is better spent on a bigger, badder amplifier or brawnier speakers. Hasn’t it?

Cambridge Audio Azur 851N

All of which leads me to Cambridge Audio’s Azur 851N network player, DAC, and digital preamplifier. It retails for $1799. It’s really freaking good.

Frugal flagship

Cambridge Audio proclaims the Azur 851N as their “Flagship” network player. Its sibling, the Azur 851D ($1695), is the company’s “Flagship” DAC -- but the 851N’s DAC section is identical to the 851D’s, for only $100 more. The extra cash ostensibly gets you the company’s standalone CXN network player ($999) built-in. At first blush, then, the 851N looks to be something of a bargain.

The Azur 851N has clean, utilitarian lines. It measures 16.9”W x 4.5”H x 14.7”D, weighs 17.9 pounds, and is available in silver or black. This is no simple box of folded metal. The faceplate is of 3/4”-thick aluminum, while the top and side panels are slabs of brushed aluminum. Hex screws secure the top panel, with its two long slot vents. For the money, it’s a modestly handsome component.

The 851N’s front panel is dominated by a 4.3” color screen. To the right of this are the player controls, including Play/Pause, Stop, Last, and Next, and a large Volume knob with a bit of play. Pressing this knob brings up the 851N’s menu system, which is navigated using the Volume control; a Back button to the right of the Volume knob lets you return to the previous menu display. To the left of the screen are buttons for: On/Standby, Info (to select the screen layout), Home, Filter/Phase; and, in the top left corner, a USB port for use with thumb drives and the like.

The rear panel boasts a wide range of digital connections: three additional USB sockets, one of them for use with the included Wi-Fi antenna; Ethernet; two pairs of coaxial and TosLink inputs; a USB 2.0 input; AES/EBU input/outputs; and coaxial and TosLink outputs. There are also balanced and unbalanced analog outs; RS232C, IR, and Control Bus ports; and the usual mains inlet and master Power switch. There was also something I hadn’t seen before: a ground-lift switch, which Cambridge suggests should be used to eradicate the dreaded hum that, at some point or another, we’ve likely all heard.

Cambridge Audio Azur 851N

Cambridge’s RC-8/SM remote control is fully featured and pretty busy. It has the usual input and volume buttons, buttons that mirror all functions found on the 851N itself, and one labeled Backlight: press this to illuminate all of the remote’s buttons for a few seconds. Once I’d set up the 851N, I never had to touch it again, so credit is due there.

At the heart of the 851N is a pair of Analog Devices AD1955 24-bit DACs. These chips are augmented by the second generation of Cambridge’s Adaptive Time Filtering digital filter (ATF2), courtesy Analog Devices’ 32-bit BlackFin ADSP-BF532 DSP, which automatically upsamples all incoming data to 24-bit/384kHz. All of the digital inputs support signals up to 24/192. Further technical details are scant, other than to confirm that DSD64 is supported via the USB input. I can’t say that lack of DSD128/256 support much affects my largely 16/44.1 library, but I’m guessing it rules out the Cambridge for about eight or nine potential buyers. Let’s say a dozen, to be safe.

Things get more interesting in the software and streaming departments. The Azur 851N has Internet Radio, built-in Spotify Connect compatibility, AirPlay, aptX Bluetooth via an optional adapter, and UPnP/NAS support.


Hooking up the Azur 851N to my network was easy. I ran an Ethernet link from its rear panel to my Apple AirPort Express, and in less than a minute was up and running. At this point, the Azur can also begin to download firmware updates directly from Cambridge, as it did twice during the review period. The streaming DAC showed up on my Apple iPhone and MacBook Pro laptop, confirming that AirPlay worked. Next, I plugged my external USB hard drive into one of the 851N’s rear USB ports, and when I’d navigated to the Azur’s Music Library menu, I had complete access to that drive’s content. Nice. I then wired up the 851N to Benchmark’s AHB2 power amplifier via Nordost XLR cables, in turn wired to my Definitive Technology Mythos ST-L speakers via DH Labs Q-10 Signature cables, and was in business. While I took advantage of the 851N’s volume control to use it as a digital preamp, others may use it only as a DAC with a fixed output level.

With everything up and running, I downloaded to my Apple iPhone 6 Cambridge Connect, the 851N’s dedicated iOS application (an Android version is available). The app immediately found the 851N and gave me full access to the streamer. Using Cambridge Connect, you can turn the 851N off and on, adjust volume, select among inputs, browse available Internet Radio stations (such as my local NPR affiliate), navigate networked music libraries (e.g., my external USB drive), and stream music directly from the device the app is installed in. The app worked quite well, though it had a few problems, primary among them navigating my iPhone’s iTunes library: While I could easily search by album, artist, genre, or song, when I clicked on an individual playlist, it simply listed all the songs on the phone in alphabetical order. Not a huge problem. I’m guessing a software update will eventually address this; from an iDevice, one could just as easily use AirPlay.

Cambridge Audio Azur 851N

Speaking of which, AirPlay proved a middling experience. Less than two minutes after turning on the Azur 851N, I was playing music from my iPhone. I never had any dropouts, and the sound quality seemed within a stone’s throw of what the 851N was able to do with content directly off my external drive. What I did consistently encounter was a very low-level crinkling noise whenever I began playing a file. Numerous times, I tried playing the same song via AirPlay, then from my external USB drive, to ensure I wasn’t imagining this. It sounded almost like a very mild distortion, though I suspect it’s how AirPlay is implemented. I could hear it only when I played soft passages of music quite loudly, so it was hardly a major problem. If I listened only to more raucous tunes, I may never have heard it at all.

Finally, there’s that tiny Filter/Phase button on the 851N’s front panel (labeled Filter on the remote). The 851N comes with three filters: Linear Phase, Minimum Phase, and Steep. Linear Phase is the default setting for all inputs, and while the time-coherent reconstruction filter does feature a small amount of pre- and post-ringing, I found Linear to be the most articulate, focused, and concise sounding of the three options. Minimum Phase, which eliminates pre-ringing, and Steep, which has been “optimized for stop band attenuation of close-in aliasing images,” both sounded slightly more diffuse and smeared in comparison. These differences were incredibly subtle; it took me quite a while to decide that Linear Phase sounded best to my ears. Holding down the Filter button for two seconds inverts the phase. This sounded just wrong to me, so I left the 851N in correct phase.


No DAC should have a tailored frequency response, and the Cambridge Azur 851N didn’t. It sounded as flat and linear as every other DAC I’ve heard in the past couple of years. For the first week or so of background listening, I struggled to pick out what set the Cambridge 851N apart from the Benchmark DAC2 DX that had been in my system for the preceding several months. Slowly but surely, I spotted a couple of fine differences.

Cambridge Audio Azur 851N

First and foremost, the 851N was hugely resolving. I threw on “We’re All We Need,” from Above & Beyond’s We Are All We Need (16-bit/44.1kHz ALAC, Anjunabeats), and was blown away by the clarity of Zoë Johnston’s voice. Owing in part to the Benchmark AHB2 amp’s abyssal noise floor, Johnston’s voice emerged from complete darkness, but with a richness, fullness, and dimensionality I wasn’t wholly prepared for. Organic is an adjective I usually save for amplifiers that can unearth from a recording a certain harmonic density, and let a musical performance’s blood and fire flow and burn in the way that only a tubed or class-A circuit can. The 851N was able to reproduce that very same organic quality. It neatly avoided any aspect of sound that could be called sterile, yet never strayed toward anything that sounded warm. Tonally, the Azur 851N was superb. In this recording, Johnston’s voice has mild leading and trailing sibilant edges; these the Cambridge deliciously reproduced, with only the slightest emphasis. This Goldilocksian “juuuuust right” quality reminded me of Arcam’s FMJ D33 DAC ($3299), which I reviewed in 2012.

“Drowned World/Substitute for Love,” from Madonna’s Ray of Light (16/44.1 ALAC, Maverick), highlighted the closest thing to a sonic signature that I could hear from the Cambridge. No one would ever describe the Material Girl’s voice as being airy or extended, and by 1998, when this album was released, her delivery was more soulful and deliberate, her voice trending notably lower in range. The 851N struck me as being most at home voicing this new reality of Madonna’s vocal range. Other DACs, such as Benchmark’s DAC2 DX, seem to imbue Madonna’s singing on this track with a touch more verve and impetus, shedding greater illumination on the top end of her delivery. By contrast, the Cambridge was more reserved, yielding a more pronounced lower midrange.

Next up was Rob Zombie’s “Dragula (Hot Rod Herman Remix),” from the excellent soundtrack for The Matrix (16/44.1 ALAC, Maverick). This mix makes the original Rob Zombie cut sound mundane, even campy. It’s a hurricane of synthesizers, quick-fire drum work, and elongated voices that seems all too eager to blow out a tweeter or two. I dialed in an uncomfortable amount of volume and let loose. The 851N unraveled it all with ease. From Zombie’s voice, which fades in and out of the background throughout, to the two-dimensional, late-’90s electronic effects and the cacophonous mass of electric-guitar chords, the 851N seemed to get it all just right.

Cambridge Audio Azur 851N

In the Orpheus Chamber Orchestra’s recording of the third movement, Allegro, of Spring, from Vivaldi’s The Four Seasons (16/44.1 ALAC, Deutsche Grammophon), the sound of the top end of soloist Gil Shaham’s violin was never particularly sparkling or extended. Other DACs have rendered Shaham’s quick bowing at about 2:40 with a high-frequency brittleness that can sometimes sound exciting and invigorating but that ultimately grates. But that same characteristic can tend to highlight the boundaries of a recording space, to make the sound particularly spacious. The Azur 851N didn’t possess this stridency. Ever the gentleman, its more respectful, genteel nature seemed allergic to such a practice. When Shaham’s violin performs its dancing routine in this movement, the soundstage turned cavernous through the Azur, but never artificially so. The 851N seemed to get it just right.


I mentioned Arcam’s FMJ D33 above, but it’s been too long since I’ve heard that DAC to make any meaningful comparison of it and the Azur 851N. Benchmark’s DAC2 DX, however, proved a perfect sparring partner for the demure Cambridge. Costing about $100 more, the Benchmark offers nothing in the way of streaming capability, but does have a highly capable headphone amplifier. On the grounds of sound quality, only the narrowest margin separates these two high achievers.

Whereas the Cambridge produced a hearty, robust sound that was easy to fall for, the Benchmark is more of a precision instrument, able to cut across sonic boundaries with slightly greater acuity and definition. It’s also a bit lighter on its feet, with an incisiveness that takes a more penetrating look at a recording, to ultimately reveal more microdynamic insight. But the gap in ability between the two DACs was quite narrow. What the Azur 851N gave up in litheness and resolution it won back in musicality. More often than not, I was more satisfied with my music when the Cambridge was in play.


Cambridge Audio’s Azur 851N is a heck of a digital front end. As a streamer, it performed with nary a hiccup, and I suspect that if I’d had a proper NAS setup, my gratification would have been even greater. While its implementation of Apple AirPlay wasn’t as flawless as I would have preferred, the Azur 851N’s DAC section is a real honey, producing the kind of dulcet sound that any audiophile should be able to appreciate. Combined with an intuitive user interface and a raft of digital inputs and outputs, this unassuming streaming DAC should have no shortage of admirers.

. . . Hans Wetzel

Associated Equipment

  • Speakers -- Definitive Technology Mythos ST-L SuperTower, KEF LS50
  • Earphones and headphones -- NAD Viso HP50, Shure SE535LTD-J
  • Power amplifier -- Benchmark Media Systems AHB2
  • Integrated amplifier-DAC -- Hegel Music Systems H300
  • Digital-to-analog converters -- Arcam irDAC, Benchmark Media Systems DAC2 DX
  • Source -- Apple MacBook Pro running iTunes
  • Speaker cables -- DH Labs Q-10 Signature, Dynamique Audio Caparo
  • Analog interconnects -- Dynamique Audio Shadow RCA, Nordost Blue Heaven LS XLR
  • USB cables -- DH Labs Silversonic, Nordost Blue Heaven

Cambridge Audio Azur 851N Network Music Player-DAC-Digital Preamplifier
Price: $1799 USD.
Warranty: Three years parts and labor.

Cambridge Audio
Gallery Court, Hankey Place
London SE1 4BB
England, UK


North American distributors:
Audio Plus Services (US)
156 Lawrence Paquette Industrial Drive
Champlain, NY 12919
Phone: (800) 663-9352


Plurison (Canada)
313 Marion Street
Le Gardeur, Quebec J5Z 4W8
Phone: (866) 271-5689