Briefly -- as has been explained at length elsewhere -- the key to the problem, elambo, is that the sample timing of most conventional AD runs off an internal crystal clock. Crystals have a
fixed oscillation rate and this varies in very small -- but still significant -- amounts from one crystal to another and that is why we normally must use a
phase locked loop in order to try to synchronize more than one AD unit when they will be run in tandem. In a simplified sense, the PLL is
continually resetting the clock circuitry of the slaved unit in order to sync to the incoming clock.
And that tends to produce
increased jitter -- timing inaccuracy in the sample taking -- relative to the unit's own internal clock, which, as you will no doubt see, means decreased sample accuracy. This is a fact of multiple AD life and must be lived with when using multiple AD units yoked together.
EDIT/appended: It might help to think of clock accuracy as having two, separate, distinct, aspects: 1) regularity of spacing from one sample to another and 2) long scale accuracy, ie, accuracy against some external standard (for instance, International Atomic Time) The problem we have is that trying to synchronize a crystal based clock to an external source in order to gain greater objective accuracy (#2 above) we end up sacrificing the regularity of sample spacing (#1 above) and that manifests as dynamic inaccuracy.
Max Gutnik, as you'll see if you follow the threads below does not dispute these basic facts, although he does suggest that Apogee's noise shaping technology makes the increased jitter sound
better than the actual, accurate sampling to test subjects in his company's testing -- unfortunately, those tests have apparently
not been published or peer reviewed, so we'll have to take their word. (Updated info on that is welcome!)
At any rate, subjective preference is
just that -- and I would be the last to try to tell someone what they
prefer.
But jitter is something that can be easily measured and such measurement tells us that slaving-related jitter is a fact of life.
Below are links to more threads on the topic, elambo.
You'll be able to see everyone's thinking.
You're absolutely free to your own opinion and interpretation -- but I hope you will not promote unsubstantiated opinion as
fact. I suggest that you find some credible, authoritative sources to back you up.
[BTW, I think you will see an evolution in how Max phrases things over time, incorporating more careful qualification to his statements as the arguments become more refined.]
Good Clock - Bad Clock? Low End Gear High End Clock...
But
here is the mother of all threads on the supposed benefits of external clocking as well as some very pointed and science based refutations by converter design legend Dan Lavry and others of some of the claims:
PSW Recording Forums: Dan Lavry => Proper word clock implementation
(Max and others at Apogee appear in that thread; make sure you follow their dialog with Lavry, which is pretty interesting if you're interested in this stuff.)