明白楼主转载的意图，直击要害，PF。贴一段载自BIG BEN使用说明书的内容。
Master Clock and Conversion
To understand the importance of the clock signal during the A-to-D and D-to-A conversion, it’s useful to examine the similarities between film and digital audio, two media which capture reality by recording and reproducing small slices of that reality.
Much in the same way that a film captures fluid motion with discrete, regularly timed still pictures, digital audio technology captures audio waveforms with regularly timed snapshots called samples. In each case, the timing regularity of the slices is paramount to successfully reproducing the original event.
For example, just as a hand-cranked projector will cause a perfectly normal film to appear jerky and unnatural, timing inconsistencies (known as jitter) in a digital-to-analog converter add inaccuracies to an otherwise good digital audio signal. Worse, if a hand-cranked film camera were used to capture a performance, even the most stable projector couldn’t remove the instability of the movement recorded on film. Likewise, jitter anomalies encoded during the analog-to-digital stage can never be removed further down the digital audio chain. The overall quality of a digital system is determined by the quality of the A-to-D and D-to-A converters; the most stable clock possible ensures the most consistent timing, and therefore the highest quality, for these stages.
Master Clock and Device Synchronization
A Master Clock also ensures the synchronization of all devices in a studio, allowing any possible digital connection to be made seamlessly without clicks, pops or digital hash. To understand the requirements of a clock signal, consider the analogy between the digital studio and a musical ensemble.
In order for a musical ensemble to play together successfully, each member must perform his part at a common tempo. Likewise, each device in a digital studio must transmit and receive digital bits as dictated by a common clock signal. The larger the ensemble, the more difficult it is to play together without a conductor - imagine the resulting cacophony if each player in an orchestra followed the tempo of his neighbor. A similar situation arises in the digital studio when each device receives a clock signal from its neighbor - timing differences between devices can cause digital bits to be dropped when the studio must “play together”, for example while transferring or mixing digitally.
On the other hand, when each member of the orchestra follows the tempo set by a conductor, even a large group of musicians can play precisely in unison. Likewise, when each device receives a robust and precise clock signal directly from Big Ben, even a large digital studio can operate in perfect synchronization.
