Digital Processor Reviews

I moved on to 1971 and "Baby Blue," from Badfinger's Straight Up (CD, Apple)—the song used to glorious effect in the final scene of the TV series Breaking Bad (a reference to the blue meth that Walt perfected). It begins with that famous crunchy guitar riff, dropping into classic early-'70s rock production: simple and compressed. There are Beatles signs all over this album: the arrangements, the sound, the vocal harmonies, the guests (George Harrison), the label (Apple), the producers (Geoff Emerick, Harrison), the keyboard player (Klaus Voorman).

Still, Badfinger managed to transcend the "Beatles clones" moniker deserved by so many others simply by writing some great songs, the best-known probably being "Without You." But "Baby Blue," coproduced by Todd Rundgren, has always been the one for me, and through the Azur 851D it filled the room with all the heaviness and flow one could ask for. Not an audiophile-grade recording, it still managed to please through the Cambridge, which did a good job of smoothing a bit of the mix's brightness while leaving intact the liveness of the electric guitar.

At various times while listening I played with the 851D's filter settings, and it was quite a while before I felt I could come up with a preference: Linear Phase. The difference between it and Minimum Phase was particularly understated, though I came not to like the Steep filter. Steep added a very light opaqueness and congestion, and lost just a nanotad of the music's sense of air.

Of the two filters I preferred, Minimum Phase thickened the sound ever so slightly—an effect that might actually be preferred in some systems, but for me was just one tick too far. Nevertheless, the differences between filter settings were extremely subtle. Inverting polarity was not so subtle, clouding the soundstage a bit with most recordings, so I left the 851D in correct polarity.

Back to the music. There are three bands named Kaleidoscope that I'm aware of: one from the US, one from Mexico, and the one that concerns us here, a British group active in 1967–68 that eventually changed its name to Fairfield Parlour. Their first album, Tangerine Dream (CD, Fontana), released late in 1967 and containing several psychedelic, Syd Barrett–ish gems, belongs in any collection of music of that era.

Comparisons
When I began this review I still had on hand the MSB Analog DAC (reviewed in April 2014) and Antelope Zodiac (September 2014), and once in a while I dropped these DACS into the system to compare with the Cambridge. This was maybe not a fair comparison—the Cambridge costs only a quarter the price of the other two—but the 851D never embarrassed itself. Listening to Kaleidoscope's often dodgily recorded album did highlight the differences, however. With the higher-priced DACs there was an ease to the listening, especially in the denser passages, that the Cambridge had a bit of trouble with. The MSB and Antelope earn their keep by simply revealing a more honest sound all the way around—for example, with "Dive into Yesterday" or "(Further Reflections) In the Room of Percussion," both brought all of the swirling instruments into slightly better focus while adding a tiny bit more heft and authority to the bottom end.

When I dropped in the more comparatively priced Benchmark DAC2 HGC ($1995), the gap closed just a bit. Everything felt more under control with the Benchmark, with more of a sense of focus all around—which was more pleasing in my system, and let me hear a bit deeper into recordings. For example, switching between DACs with a 24/96 mastering of Yes doing Paul Simon's "America," from 1972 (a bonus track on the DVD-Audio edition of Fragile), the upper details seemed ever-so-gently scrambled with the Cambridge—as if the control had slackened a little.

I also did some headphone listening, comparing the 851D with the Antelope and Benchmark, and here the gap widened a bit more. The more expensive DACs simply sounded better through my Grado HP1 headphones.

Finally, I compared the Azur 851D with Cambridge Audio's entry in the USB micro-DAC category: the DacMagic XS ($189). This was probably not even kinda fair. The 851D generally added more life and sense of realism, and the dynamics and bottom end were noticeably greater and more under control. While the DacMagic XS is a worthy step up for your computer, the 851D's feature set and sound justify its much higher price.

Bluetooth
Other than the DACMagic, all of these comparison DACs are configured similarly to the Cambridge: multiple digital inputs, balanced and unbalanced outputs, volume control, and, with the exception of the MSB Analog, a headphone amp. The one thing the Cambridge had that the others don't was its BT100 Bluetooth dongle, which you can plug into the rear panel to add streaming from your phone or tablet. Over time, I came to realize that this is a great feature! Cambridge's implementation of Bluetooth uses the aptX compression algorithm, which imposed on the sound a bit of "FM radio" quality, though this wasn't as bad as I'd expected. The most noticeable artifact was high-frequency hash or smearing in cymbal crashes and such, but the bottom end, dynamics, and overall imaging tended to come across intact.

When I streamed CD rips from my iPad or iPhone, the sound was more than acceptable for casual listening. What convinced me of the Bluetooth input's importance, however, was what happened when friends dropped by. I realized I could pair their phones with my system, which allowed them to confidently play their own music then and there, which they loved.

Conclusions
The Cambridge Audio Azur 851D has bang for the buck all over the place. It approached the sound of DACs costing four times as much—closely enough, I feel, to satisfy most audiophiles on a budget. However, if you can forgo some of the Cambridge's features, the Benchmark DAC2 HGC, for $500 more, edged out the 851D in the sound department, especially through headphones. But the Cambridge offers a more conventional and ergonomically friendly design, with scads of digital inputs if you need them.

And the Azur 851D's Bluetooth-streaming feature surprised me with its usefulness, leading me to conclude that this $1649 DAC-preamp deserves a listen if you're looking for a high-value heart for your system and don't mind the conservative outfit.