I seem to recall reading something by one of our dCS team explaining how traditional clock jitter specs are not very helpful in understanding effect on the (dCS) DAC. But I am probably misremembering.
But Anup is correct: different DAC chips and architectures need certain qualities of clock performance in order to sound their best. When I made the move from my TotalDAC rig to my MSB Select II, I ponied up for the femto 33 clock, because it made a difference. To my ears, the Vivaldi Clock improves (audibly and not insignificantly) the Vivaldi DAC, and I assume that’s because its performance has been engineered for the RingDAC. I’d probably like to understand the “how” better, but dCS is understandably coy about details. And the Cybershaft OP21A seems to help further (unfortunately, with one step further removed from the “how”). If and when we get a Vivaldi successor, I suspect we—and our wallets—will get a chance to re-evaluate these matters. 