Clock choices for Rossini DAC

I have owned a Rossini DAC and am considering to further improve SQ by setting up clocking method or adding an external word-clock.
I have learnt from community that dCS does not accept external clock directly to replace internal clock, the external clock is just a reference to make PLL more accurate. Based on this, may I think that setting Rossini DAC as the master clock to synchronize with CD transport is the most efficient way instead of buying an external clock like Rossini clock? Since no matter how accurate or how low phase-noise is the external clock, it will not work directly and PLL of Rossini DAC is always dominating.

Hello Adam,
Welcome to the forum. I’m not sure I fully understand your question, but, to my knowledge, this is the most effective way to improve the SQ of the Rossini, with respect to clocking only:

(a) Connect Vivaldi clock
(b) Connect 10MHz atomic (reference) clock to Vivaldi clock, like, for example, the SRS Perf 10

A number of users on this forum use this configuration, including, if I recall correctly, Ben (@all2ofme)


I do not understand your deduction regarding a dominance of Rossini DAC’s PLL. Are you able to clarify?

Of course if you are correct then the addition of an external clock will be ineffective and the choice of which used, irrelevant. However should you have the opportunity to audition a choice of external wordclocks with your DAC you will find that this is not the case.

You seem to be asking what is the most efficient way of synchronising Rossini DAC and a CD transport. If cost is the arbiter of efficiency then using the wordclock output of Rossini is a good option as far as synchronisation is concerned ( assuming that the transport has a 75 ohm wordclock input). However it may not be judged as the optimum overall. Whichever, the resulting ffect may be judged as subtle and this will therefore also need to take account of the overall system ( and its resolution), your sensitivity to this aspect and the type of music listened to.

Thank you @PAR , and also @keiserrg for your prompt reply.
Allow me attach the links from where I have got the information, although it was talking about Bartok. I do think it’s the same on Rossini.

No doubt an external clock might always helpful on SQ, my question is just regarding what’s the most efficient way with less expense.


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Hi Adam,

This is a valid question to ask - since the Rossini DAC’s PLL will filter out any short-term adjustments to the signal sent from a Rossini Clock, is it a worthy addition? The answer is definitely yes. Since the PLL in the Rossini DAC is entirely our own hardware and software, we can operate it to best make use of the external clock source - changing the PLL’s filter frequency over time for example.

A completely tight synchronisation of the clock in the Rossini DAC to the clock inside the Rossini Clock would result in more jitter at the Ring DAC, as interference is picked up on the clock cables for example. The same thing would happen to a larger degree if we switched off the Rossini DAC’s clock crystals and just used the Rossini Clock’s crystals to directly control the Ring DAC circuit inside the Rossini DAC - more jitter as the clock signal is travelling a further distance.

We do enough filtering in the PLL that it removes any interface jitter picked up from, for example, the clock cables - but not so much it negates the benefit of the external Clock. And, we can continue adjusting and optimising over time to make the best use of the stable reference clock signal.

So I suppose, the heart of the question isn’t whether the Rossini Clock will be of benefit, but rather if that benefit is:

  • Audible
  • More significant than simply connecting the Rossini DAC to the Rossini Transport with a clock cable (which will also be a benefit over not using a clock connection at all)
  • Worth the investment

The honest answer is that only you can be the judge of if the benefit is worthy of your investment. I would highly recommend auditioning a Clock with a dealer if you have the opportunity to, so you can hear the sonic benefits it brings and make that decision for yourself.

Adding a Rossini Clock is definitely a technical improvement over simply using the clock output of the Rossini DAC, and that really does translate to a significant lift in the sonic performance of the system. The tech is sound, but hearing is believing, so get yourself in front of a system with a dCS DAC and Clock if you can and have a play! :slight_smile:


Thanks @James !
Your professional explanation is always persuasive and I am completely convinced now.
I think it’s worth the time to try the combination of Rossini DAC and Clock.


I’m so thankful for this explanation @James as another leading DAC maker, with a different product architecture, cites jitter from the clock cable as a reason to simply put a better clock inside the DAC, and as a result I’ve wondered about this for 2 years (!)

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Excellent reply James!

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Just chiming in as I recently went from auditioning for Rossini Clock and then buying it and now living with it for the last 2 weeks. (I have both Rossini Dac and Rossini Transport)

Here are the things that I found in last 2 weeks where clock shines -
1.The soundstage became tighter. Now, with a change in volume, I hear the integrated full imagery moving back and forth. Without a clock, the soundstage kind of gets readjusted.
2. With bad quality recordings, it improves the fluidity in the sound, and reduces harshness (in comparison to ‘without clock’).
3. With very good quality recordings (especially with CDs and SACDs played using transport), the sound seems now pretty close to the organic sound of Vinyl (I have Rega Planer 10 with Apheta 2 cartridge).
4. Network streaming (I use Quboz) has now got a more punchy/full-bodied sound.