jitter

Sadly, this Stereophile review of a dCS Rossini did not do comparative tests.

https://www.stereophile.com/content/dcs-rossini-player-rossini-clock-measurements

If we had, then we'd be able to see how the bare unit compares to other bare units and how much the clock improves or changes the results.   It is interesting to compare the jitter performance to the $1,999 Benchmark DAC, which costs 1/4 of the dCS clock alone. 

While personal preferences trump all measurements, I have trouble thinking of an external clock of $8k as being a good value.

@antigrunge2 Yes they do. And some have published papers explaining the difference in error between a built-in clock and an external unit is different. You may get a better clock in an external unit, but by the time it’s made it inside the DAC the delta in performance may vanish.

Mytek, for example, recommends an external clock only when needed in a studio setting, but still offer the connection.

My personal feeling is, you should listen for yourself and determine if it’s even different or not and whether that difference is actually better for your tastes.

Further, in the last 20 years the performance of internal clocks has improved so much I can’t justify an external clock anymore.  Redbook performance (44.1kHz/16 bit) has gotten so good that if a DAC sounds significantly better with high rez music I blame the DAC and not the bit rate.

That Esoteric and other offer external clocks is not, IMHO, a sign of superiority of the idea. One could argue that they put an inferior clock in to begin with and then make you pay for the difference you’ll undoubtedly hear.

BTW, recording studios use Master Clocks to synchronize multiple ADCs or DACs together. Not to reduce jitter.

As I understand it, while external clocks are excellent the distance due to the cable lengths actually can increase jitter vs. an internal clock of the best DACs today.  The internal femtoclocks used today sit right next to the DAC so don't have the same distance issues.  This is similar to the need to keep RAM right next to the CPUs.

It’s quite possible that an external clock can merely change or worsen jitter performance.

I don’t think jitter causes dropouts. Are you using WiFi? If you are, that’s more likely the issue I think.

Networks have jitter, but it’s defined differently than what we think of in audio. It’s variance in packet timings and if bad enough, can certainly overwhelm a DAC’s jitter reduction/buffers. If it's bad enough though it's called "packet loss" instead. I usually have a good Internet connection but I still set my streamer’s buffer relatively high to 10 seconds or more to avoid issues.

If on Wifi, use a free Wifi analyzer for your PC or phone to make sure you have a strong signal that isn’t shared by many other router signals.

No device is completely immune to jitter, but it did get remarkably better after the year 2000.  Any device can be overwhelmed by upstream jitter, and testing with medicore reclockers have shown this.

In general I will say that a good streamer with multi-second buffers should have vanishingly low jitter to add to a DAC's output.

Jitter during recording is different. It shows up as sample errors and that gets baked into the recording. I imagine it would show up as Harmonic Distortion or, based on a quick reading, reduced signal to noise.

What I mean by sampling error is that the value that is written down won't be correct.  For instance if the ADC would record 2.0 V at T0 with a perfect clock, with ADC jitter it might record 1.99997 or 2.0004 instead.

As far as I know it doesn’t produce the same noise side bands that jitter in playback does.

Still, both should be minimized for the best musical recording experience. :)