Packed with most of the features and functionality that has popped up over the past decade or so, Cambridge Audio’s new flagship DAC is a veritable ‘greatest hits of digital’ in one convenient package. It’s certainly big and heavy for a DAC, and is very well finished for its £1,000 price tag. This company has made a real effort to pull its products beyond looking and feeling like budget designs, and the 851D is no different. What dominates the fascia is a large volume control and backlit, reverse-video LC display. The latter has eight inputs – including a plethora of conventional digital ins, plus asynchronous USB and aptX Bluetooth via a bundled dongle. This volume control can be bypassed, and the unit configured to work as a DAC, or it can enabled and used to drive a stereo power amplifier such as Cambridge Audio’s own 851W.
The unit offers twin Analog Devices AD1955 24-bit DAC chips, working in dual differential mode, and comes fitted with ATF2 audio upsampling to 24-bit/384kHz. Developed in conjunction with Anagram Technologies of Switzerland, it’s an evolution of earlier work the company did for previous Cambridge Audio DACs. It uses a special adaptive time filtering algorithm that de-jitters all digital sources and can also upsample them to 24-bit/384kHz resolution. Upsampling itself is not new but the 851D’s implementation is unique to Cambridge Audio. It is claimed that it makes for a substantially smoother, more phase-coherent sound, as all the digital number crunching is taken so far away from the audio band that it can’t interfere with the resulting analogue signal. Although not a completely unanimous view, many listeners feel it’s a worthwhile feature. User selectable digital filters – linear phase, minimum phase, steep – are provided.
This largish (115x430x360mm, 7.5kg) box features a choice of unbalanced RCA or balanced XLR outputs; generally the latter is preferred if you have a matching power amplifier that can use this facility. There’s a full-size, 6.3mm front panel mounted headphone socket, and company says it has a bespoke “high-end, low distortion” headphone amplifier. Fresh juice is delivered by the toroidal power transformer and a system of multiple cascaded regulators; each channel has its own transformer winding and analogue and digital power supplies are entirely separate, with significant effort going into ground return current paths, the company says. These all sit in a rigid metal chassis, to which a brushed aluminium fascia, side and top-plates are attached, as well as low resonance feet. The results is a sleekly finished product that feels very sturdy.
Compared to Audiolab’s popular M-DAC, this unit gives the sense of being the font of all detail. It brims with information about the recording, from the precise location of all the instruments across the stereo soundstage, to their relative front-to-back spatiality. It locks instruments in the mix very boldly to precise points within the recorded acoustic, and never lets go. It seems very good on leading edges too, giving a very ‘etched’ sound that you can’t fail to ignore.
Tonally, it’s a little on the ‘well lit’ side. It’s not bright or hard, but it lacks the deep, dark, velvety tonality of Chord Electronics’ Chordette Qute EX DAC which is only a few pounds more expensive. Whereas the latter sounds quite sumptuous and silky, the Azur 851D is a good deal more upfront and in your face – think The Ramones to the Chord’s Barry White. This isn’t a criticism necessarily, but you’ll not want to drop it into an already forward sounding system. Feed the 851D a brightish recording like Ride’s Twisterella and you’ll feed every strum of the boys’ guitar strings resound around the room, as well as the heavily EQ’d and compressed vocal tracks pushing out at you with a vengeance.
The switchable filters help here, with the Linear setting coming over as the most forward sounding in my review system, and Steep being the smoothest. The others have a subtle effect, to varying degrees making the music marginally more effusive but at the expense of a subtle amount of air and space. Still, in all fairness a well chosen interconnect cable would help better here – and you’d be thinking more along Tellurium Q lines than Nordost. Give this DAC a good, well balanced recording though and it’s in its element; Yellow Magic Orchestra’s Technopolis is a track I’ve heard thousands of times, and was surprised to be honing in on small nuances I’d not quite heard before. Make no mistake, this is a very high resolution device.
What better than than feeding it with some hi-res music. Via USB 2.0 the 851D hooked up to my Mac without the need for a driver, giving sparkling 24-bit/192kHz sound. REM’s Texarkana was rendered with dizzying amounts of detail – you have to get into dCS Debussy territory at nearly ten times the price to really improve of what the Cambridge Audio gets out of the computer equivalent of the record groove. At the same time, feed it the beautiful, brooding Snowflake (24/96 WAV) by Kate Bush and it’s once again impressing you with its spaciousness, and the rock-solid imaging within the recorded acoustic. It smoothens up with higher resolution digital files, the DAC seeming to fill out tonally and gain a bit more body. Bass isn’t bad at 16-bit, but with hi-res it gets more generous and better rounded, just as it should.
Bluetooth works well; the 851D gave a punchy rendition of Grace Jones’ Slave to the Rhythm from an iPad. But just as the hi-res takes this DAC to warmer, fuller climes, so the aptX Bluetooth takes it in the opposite direction. The lower resolution file quality makes for a slightly plasticky feel to the music and lighter low frequencies – although it certainly retains its rhythmic snap. Although not quite as ‘hi-fi’ as its proponents would have you believe, I’m a big fan of this connection method and regard it as really useful extra functionality for this DAC. There are sometimes when you just want to play a track or two while you’re doing something else, and Bluetooth is brilliant for this.
This is an extremely good DAC then, giving a powerful, finely-etched sound with excellent spatiality. Yet it’s a little more of a ‘Marmite’ product than some – its explicit and upfront sound may put some people off who look for a more mellifluous presentation. For example, the Chord Qute DAC seems better able to get into the rhythmic subtleties of a song, it swings along with a more instinctive feel for the groove on Sister Sledge’s We Are Family. By contrast, the Cambridge Audio goes it to tell you all about the recording, whether the bass guitar had a slight buzz on a fret or if the second backing singer was getting over a cold. It’s a more technical, cerebral presentation; it’s no less capable, but some will think it less satisfying. Tonally too, there are others that sound warmer and more sumptuous in the bass – something to keep in mind when system matching.
An excellent digital converter, it’s one of the most detailed, insightful performers this side of the multi-thousand pound super-DACs, and many prospective purchasers will be dazzled by its fine sound, wide variety of connections and sturdy build. Moreover, if you’ve already got a power amplifier, it makes great sense to use it as a preamplifier, saving you money and giving better sound along the way.