DACs, external clocks, and what's what

Also, your purchasing process seems to separate the DAC then decide on a clock.  Because of limited budgets, the decision should be Both DAC+clock combined simultaneously within budget.

So the decision within budget should be like: DAC A standalone vs DAC B + external clock + cabling vs DAC C standalone vs DAC D + PSU + clock + cabling….etc 

@kerrybh wrote:

I’m certainly not a DAC designer. I think no one knows more about this stuff than Meitner, or the MSB folks, but this is quite confusing, at least to me. Lots of stuff in our hobby comes down to subjective preference, but this seems to be a case where one side must be right and the other is wrong. Which is which? If you think an external clock provides a substantial improvement, how so?

Well for one, I know that my external master clock, the Grimm Audio CC2 connected to my source wordclock input, makes a substantial improvement in my setup. Audio friends of mine are similarly convinced of its merits. So, no debate here. 

As to the how of it, that’s a technical matter I’d rather let Mr. Eelco Grimm and his buddies explain here, here and here. What I can say myself is that of the DAC’s and sources I’ve owned over the years I’ve always preferred the AES/EBU digital input/output route (years back I did use the Audiophilleo 2 with battery PSU over a BNC input), same with my current DAC, and as an S/PDIF protocol that means the source is the master clock to which the DAC is then slaved (contrary to asynchronous USB protocol where the DAC is the master clock).

Even though the incoming AES/EBU signal is reclocked in the DAC and as such claimed, with modern DAC’s in particular, to being more impervious to the clock precision (or lack thereof) coming from the digital source output, I can state with certainty that in my setup context at least the Grimm Audio master clock makes for vastly improved sound quality overall. In which way? A smoother, tightened (but not unnaturally so), more clearly contoured and subjectively deeper low end; a more clearly focused and natural midrange; an even more finely "grained" and delineated top end, and better spatial acuity. Dynamics and tonality appear improved as well. Truly, the presentation as a whole is just more natural, coherent and informative in an unforced manner.

Every connection (connector + cable) is a potential jitter source to boot, but with the Grimm it’s connected with a 75 ohm BNC-BNC clock cable to the pro Marian sound card wordclock input as per the prescribed protocol impedance. What I will look into next with an upcoming new digital AES/EBU cable is to make sure it’ll be assembled by a technician to meet the 110 ohm impedance required here, which is minimizing at least another jitter source. We’ll how that fares out. 

To those who believe an external master clock has to be priced a certain amount to make a worthwhile difference (in which context?, I might add), and can only say the Grimm at ~€1,450 is worth every penny in my system and btw. is the exact same master clock used in their MU1 and MU2. Perhaps that should tell you a thing or two. 

Coming down to it experiences with external master clocks should be viewed in the specific setup contexts, their implementations and products used. What’s the use of generalizations pointing to one direction or another? Do some research and find out how it applies to your system context and compatibility here, and then decide whether to try out a master clock option. It does appear though many are skeptical as to the importance of clock precision with reference to (poor?) theory or very limited experience, which is unfortunate, I find.

@phusis I don't doubt for a minute that your external clock has resulted in improvement-its foolish to question what someone else hears. That's not really the question that is at the crux of the debate that interests me. I think the designers like Meitner and the MSB guys-certainly well credentialed-would say that IF the internal clock is designed and built to a certain standard the external clock is unnecessary. In fact, I think Meitner has suggested the external clocks are "stupid." Of course, the opposite is true if the internal clock is not optimized.

On the other hand, equally well credentialed designers such as dcs, Wadax and others take a completely different view. So, the fundamental difference in design philosophy is not whether an external clock makes a difference in a particular application, but whether buying that extra box can be made unnecessary by designing the internal clock to a higher standard, which, of course, is less costly than putting the clock in an extra box.  As I said, I don't know who is right but simple logic dictates that both sides can't be right. That is uncomfortable for some, but an important question for dac shoppers.

The dac market is interesting. You have this choice, the topology choices-chip, R2R, etc, then the NOS/filterless trend-its confusing. And it seems that new dacs are hitting the market every day. Sounds like your solution works well for you which is really all that matters.

Engineering expertise ≠ unbiased opinion.
Both sides have valid advantages and disadvantages. While there are advantages to design a one box A-Z solution, there are also advantages to building separate components to optimize/update each separately to plug into a digital solution. There is no right or wrong, only the engineer’s design preference. 

There is only 1 truth is false. There is a substantial market for both.

If having “options” make you “feel” like there’s something missing or that your DAC is somehow “feeling subpar”, then it’s you, not the DAC. Usually options vs none is considered good - having additional opportunities to upgrade Sonics is better than none. If you cannot get past this emotional baggage, maybe options is not a good choice for you.

@kerrybh  I think the designers like Meitner and the MSB guys-certainly well credentialed-would say that IF the internal clock is designed and built to a certain standard the external clock is unnecessary.

This is correct in principle, but achieving "a certain standard" in practice and replicating that within the confines of a DAC can be challenging depending upon one's definition of "a certain standard." It's not a matter of who's right or wrong, but what degree of clock performance one determines to be good enough.

@kerrybh ...but whether buying that extra box can be made unnecessary by designing the internal clock to a higher standard...

Clock platforms are highly sensitive to various electronic and environmental disturbances. If we consider an external clock with extremely good phase noise performance (e.g. MUTEC Ref10), it achieves this in part by having its own isolated power supply, regulation, electronic architecture, and chassis that it shares with nothing else. Attempting to fit this standalone unit into the confines of a DAC while maintaining the same level of performance would be challenging, not unlike attempting to squeeze an upmarket standalone DAC into the confines of an integrated amplifier while maintaining its expected performance. 

What degree of audible difference (if any) an external clock may bring is dependent upon a host of variables and the perceived audible difference is subjective. What isn't subjective however, is reputable clock producers will provide actual phase noise measurements taken at the output, and phase noise @ 1-10 Hz is a direct indicator of clock quality and precision regardless of all else (including price).