dCS Rossini Master Clock Review

I was in denial for about a week.

The Rossini Master Clock arrived and I purposefully ignored its shipping box after tucking it in a corner of the dining room.

I think it was because I was so happy with the sound from the dCS Rossini DAC in my system and I didn’t want to mess with it. You know what I mean? You’ve got everything just singing and you kind of don’t want to screw with it.

But then I started getting curious. “How much was I missing?” I thought to myself. Would the sonic payoff of the upgrade see the $7,499 USD Clock squeeze even more out of the dCS Ring DAC technology platform the Rossini is built around?

It was a Friday night when I finally broke down and grabbed the dCS box from the dining room, muttering under my breath about how heavy the damn thing was, then wondering why I should be surprised that anything from dCS was anything but weighty.

Why mess with what isn't broken.

I opened up the box, unpacked the dense foam and grunted as I lifted it free of the packaging; the Clock was built like a tank and looked to be the same size and shape as the Debussy. I started pulling cables out and then shifted the Rossini DAC off the shelf to place the Clock under it and connect the two; “DAC meet Clock, Clock meet DAC” I said as I hooked up the dual coaxial cables between them.

From this uneventful first digital handshake between the two grew a musical friendship of such lasting harmony that you would have to forgive me for feeling remiss about ever separating the two.

Over the next several weeks I spent a considerable amount of time listening to the Rossini with and without the Master Clock connected to it. Those sessions would last for several days either way, and while, over time, the differences would become less apparent as I became accustomed to the sound, it was always the first hour or two switching over that sonic revelations into the deeper nature of a recording would occur. I’m not going to get into details of the Rossini here, as I did that in my previous review, so this will focus on the Clock and it’s contribution to what the Rossini was already creating.

Simple, straightforward connections.

First, what exactly is the Clock doing when it’s hooked into the DAC? According to dCS, the Grade 1 Master Clock is based on years of research and development the company executed into timing and more specifically, dealing with jitter in the digital-audio signal. The dCS Clock sports three outputs for multiples of different frequencies, in the Rossini two are utilized for timing (44.1kHz – 88.2, 176.4, and 352.8kHz sampling multiples, or 48kHz and its multiples – 96kHz, 192khz) and connect via 75-Ohm BNC cables. Syncing the clock to the DAC is as simple gong into the menu system and setting the mode to ‘Auto-Clocking (W) so that whichever sample rate is being utilized for file playback, it is being decoded by the correct clock. Dither choices are offered for both 44.1kHz and 48kHz clocks which are included to “exercise the Phase-Locked-Loop in the DAC to improve the correction of small timing errors.” I tried both while listening to either sample rates or their multiples and found that on some tracks it seemed to enhance certain instruments in the mix, or not. I ended up not using either for critical listening.

The idea behind any circuit/software design to deal with jitter is in the elimination of timing errors caused by instability in the sample timing which exists to varying degrees in all digital systems. According to dCS “Severe jitter results in timing errors in the delivery of data to the DAC, causing the analogue signal to be reconstructed inaccurately.” To find out more about clocks and jitter, please read my Audiophile Mini-Guide to Digital Audio Clocks with a Q&A featuring John Quick of dCS.

The Master Clock brings things into focus.

dCS feels that listening tests have proven to their engineers that having a dedicated master clock delivers superior sonic results over a DAC alone acting as the system’s master clock. The current dCS clock features the latest iteration of the company’s multi-stage Phase-Locked-Loop (PLL) system, outfitted with multi-stage power regulation and housed in an “aerospace-grade machined aluminium chassis fitted with tuned acoustic damping panels [to] reduce magnetic effects and vibration.” Special crystals are employed in clock systems which are chosen for their oscillation accuracy over both short and long-term timing domains. At dCS (and many other high-end companies), these crystal oscillators are pre-aged. They are “… selected for long term stability and then individually calibrated over a wide temperature range to ensure consistent optimal performance. [The] Rossini Master Clock uses a sophisticated microcontroller system to ensure smooth frequency correction as the temperature changes, and this approach gives a more stable result than either oven-controlled crystal oscillators (OCXO) or even atomic clocks,” according to the company.

So, the basic idea is of the Master Clock is to improve the accuracy of the timing signal of the sampled analog sound wave as the digital data is passed along from the source to the DAC. OK, cool. It is all about timing, which I’m learning more-and-more is absolutely critical in making our hind brains want to believe that the recorded event we’re listening to is less an approximation and more the real thing. After all, that’s what we – as audiophiles – are all doing with an inordinate amount of our time on this planet, so we might as well make it as thought-provoking and spiritual a commune with music as possible.

The setup

For this review the Rossini DAC/Master Clock combo (dCS-provided BNC cabling) were connected via Ethernet to a dedicated 100/1000 router and running the latest version of Roon via the network from a Roon Nucleus+. The Rossini’s balanced outputs were plugged into my McIntosh C2600 NOS-tubed preamplifier, which in turn was driving a pair of McIntosh MC611 mono blocs connected to Harbeth M40.1 loudspeakers. All analog and speaker cabling was a mix of TelluriumQ Black and Ultra Black. AC cabling was PS Audio. Clean power was supplied by a Power Plant 20. Digital cabling (Ethernet) for this review was Final Touch Audio and TelluriumQ.

Data Conversion Systems Ltd
Unit 1 Buckingway Business Park Swavesey Cambridgeshire CB24 4AE, United Kingdom
+44 (0)1954 233950