Digital Processor Reviews

The Vivaldi—the four-box flagship product from digital audio specialists dCS—is, in my opinion, misnamed. Vivaldi the composer was an asthmatic priest who worked in an orphanage for 30 years and died in poverty. The Vivaldi stack dedicates four separate products to converting into music digital code stored on silver discs (although you can play music—very well I am sure—on just one box, the Vivaldi DAC, footnote 1). Together, those boxes weigh about 148lb and cost some $115,000. The most expensive is the CD/SACD transport; leave that off and you can save 51lb and $42,000.

So why not choose a grander composer to name the flagship after I know: dCS has already produced a Verdi, and a Verdi La Scala—now there's grandeur—and to call it Beethoven would seem presumptuous. Still, why not call it the Brahms?

The Modernist
The dCS Bartók is named as perfectly as the Vivaldi is named imperfectly. Like the 20th-century Hungarian composer, dCS's newest DAC embodies a modernist sensibility. It isn't especially small or light, but neither is it large and ostentatious. It occupies a single box—attractive and angular in the spirit of, say, Bartók's Sonata for Two Pianos and Percussion. It weighs 36.8lb—pretty typical for a full-sized DAC—takes up far less space than the Vivaldi stack, and costs $15,000 for the version with a headphone amp; the headphone-less version costs $1500 less.

Compared to the Vivaldi stack, the Bartók is unassuming. When composer Béla Bartók died of leukemia in a New York hospital, quite close to where I now sit writing, only 10 people attended the funeral—this just a couple of years after writing his most famous work, the Concerto for Orchestra.

But Bartók was an eminent composer, and this sophisticated, modest-looking box is itself clearly aimed at greatness. Despite being stuffed in a single box—perhaps an oppressive experience for the components inside, since dCS components are accustomed to having plenty of space to stretch out—the Bartók is also full-featured, with a volume control, that headphone amplifier, and an inside-the-case version of the company's Network Bridge. That last one allows the Bartók to render into music audio data received via an RJ45 (Ethernet) network connection, delivered from remote sources—cloud storage, online apps like Deezer, Qobuz, Tidal, Spotify Connect, and Internet radio—and sources closer to home, such as the Synology NAS (for network-attached storage) I bought and assembled last month.

The Bartók also has all the usual DAC inputs: asynchronous USB, AES/EBU, TosLink, and S/PDIF. There's also a USB Type A connection into which you can plug a flash drive stuffed with music or a smallish SSD. With a dCS transport, it can also make music from SACDs, the discs' encrypted data delivered over the Bartók's dual AES connections. Via Ethernet, the Bartók can decode FLAC, WAV, and AIFF at up to 24 bits and 384kHz, and DSD128, and other formats at the limit defined by the standard. AirPlay is supported at 44.1 and 48kHz.

Analog outputs are balanced (XLR) and unbalanced (RCA) with, the company says, sufficient juice to drive an amplifier directly (remember that volume control). Theoretically, no preamp means less noise and distortion—but I and several of my colleagues have found, subjectively, that active preamps improve sound. YMMV. The Bartók's output levels are variable.

There's also the aforementioned headphone output on the front panel—two of them actually, via ¼" and balanced XLR connectors.

The Bartók has 6 PCM (footnote 2) and 6 DSD filter choices—the latter differing in how much of DSD's intrinsic HF noise is attenuated. By default, PCM inputs are upsampled to DXD, although upsampling to DSD instead is easily activated. The noise specs provided by dCS are superb—and our experience with the company suggests that JA's measurements will corroborate those.

Are you an MQA fan? Quick and others at dCS told me that their MQA implementation is superior to that in any other DAC.

The Ring Cycle
The core technology in the Bartók is the company's patented Ring DAC, which uses all discrete components, no DAC chips in sight, plus an associated "signal processing platform": a dedicated, firmware-customizable computer. The main purpose of that processing platform—quoting a document provided by dCS—"is to create a 5-bit audio stream at 64x the base rate . . . . It does this by firstly performing quite involved digital filtering (which creates very wide, very high-rate samples) before passing this through a psycho-acoustically optimized noise shaper, whose function is to reduce the number of bits by shifting quantization noise out of the audio band.

"The DAC section then . . . maps [those 5-bit samples] onto an array of unitary-weighted current sources, using a set of rather convoluted rules. The key point here is that the mapper decorrelates particular current sources from the signal, thus reducing distortion significantly."

The specific technical advantage of a Ring DAC is superior low-level linearity. Amid higher-level signals, the precision of low-level information is retained, which can make a difference in the naturalness of the musical presentation: imaging, spatial cues, etc.

A Mosaic of music
In my review of the Mytek Brooklyn Bridge—another streaming DAC—in the September issue, I wrote about how it works as a self-sufficient music device, playing music from streaming apps and local and cloud-based storage without the use of a separate, stand-alone server or computer. Like a few other streaming DACs (including my PS Audio DirectStream DAC with its optional Bridge II network card), the Brooklyn Bridge is based on technology from a company called ConversDigital. Convers creates the apps, the software, and the hardware in the box.

dCS chose a different partner in developing their streaming technology: a company called Stream Unlimited, from Austria. Stream has partnered with several other audio companies, including Naim, Primare, Simaudio, and D'Agostino. Stream's technology supports higher sample rates and allows the use of an external clock—both essential in a dCS DAC. According to Quick, since early in the company's Stream partnership, dCS has taken over steadily more of the development. Since November 2017, Stream Unlimited has served exclusively as a hardware provider; firmware and apps have been developed in-house.

As with the Mytek system, dCS network streaming utilizes an app that runs on an iPad or equivalent; the dCS app is called Mosaic, the name applying not just to the app but also to the networking code set.

While Mosaic—the app, which is available for iOS and Android devices—allows you to choose operating settings on the Bartók, its main function is delivering audio data to the DAC from various sources. Mosaic lets you play your music from a streaming service or from files stored on your network, or on a flash drive or SSD connected to a USB port on the back of the Bartók. No hardware-based server required (footnote 3).

I found Mosaic better-designed and more pleasant to use than the mConnect apps used with the Mytek streaming DAC, and to a significant degree. But the end result was much the same: Streaming with Qobuz and Tidal worked fine. The experience of playing music from my NAS was intuitive, and the music sounded great. But when I connected a solid-state drive, filled with nearly a terabyte of music files, to the Bartók's USB connection, Mosaic couldn't see the music. Why? Because my SSD came formatted with the exFAT, which is optimized for flash storage. If you're starting from scratch, you can choose a compatible format—reformatting an empty drive is easy—but if your drive is already full of data, that's a few hours of work. (The ConversDigital platform used in the Mytek Brooklyn Bridge—reviewed last month—had similar limitations.)

Soon after I started playing around with Mosaic, I discovered a list of Internet radio stations. Clicking on "High Quality," I found three radio stations from Linn—Linn Classical, Linn Jazz, Linn Radio—which, no surprise to one who regularly listens to Linn recordings, sounded great. I checked out a station called Radio România Muzical: I was expecting gypsy music, but instead I got good classical music in good sound. The "Local" tab included WKRC from Columbia University, just down the street—one of my very favorite radio stations, online or off. Sure, it's easy to find online radio guides online, but this one is, effectively, built right into the DAC—a fun feature.

The real test of any audio component, though, is in the . . .

Listening
Like many hi-fi reviewers, at Stereophile and elsewhere, I'm convinced that over time sonic differences can become apparent that are not audible, or not easily audible, in direct, rapid, A/B comparisons. Such distinctions can manifest themselves in our enjoyment—or not—of music. There is even evidence that our deeper mind is affected by aspects of the sound our conscious mind doesn't register. For these reasons and others, it's necessary not just to analyze a component but to live with it for a while, to get comfortable with it. That's a core element of Stereophile's review philosophy.

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Footnote 1: "The 'Vivaldi stack,'" dCS's John Quick told me in an email, "is most frequently sold today as a 1-, 2-, or 3-piece system to play back music in systems without a silver disc in sight."

Footnote 2: See John Atkinson's Measurements sidebar for a look at the PCM filters.

Footnote 3: dCS says, "Mosaic was never intended to replace a server (a device which stores media content and presents it on the network) and attempts to utilize the included USB type A interface to turn one of our products into a full-blown media server will be an experience rife with frustration. The simple fact of the matter is that the USB type A interface was only intended to be used with a small storage device containing a reasonable number of files." To me, though, eliminating that extra box—the server—is the main advantage of an Ethernet-enabled DAC.