Time clock sync devices

It might help to know what you're planning to use it with.  In my case, it was a complete waste of money as the device I used it with already had an excellent internal clock.

Master clocks are most often used to synchronize multiple devices in a studio environment. 

Read up on them a little.  Here's a short high-level overview 

@big_greg thank you for your answer. I recently bought a CEC transport (TL 2N) and I am planning to sync it to my dac (CH PRECISION C1), which can accept a clock sync board. I must admit that it sounds wonderfully as it is! I don’t know if it is worth buying the sync board plus a digital cable!

Hopefully someone that has owned that combination can chime in. 

Yep, clocks are critical to digital. And as  big_greg referenced one can overdue it, the internal clocks may be sufficient, adding external or more clocks and/ or mismatched clocks may disturb sound quality.  Somewhat recently I experienced what I presume was effect of this when after adding a switch to network I suddenly noticed excessively precise imaging. Other than that one episode, better clocks have always resulted in better sound quality for me. 

You'll likely get more value passing your streaming digital through a clock than the output of a high quality transport like the CEC.  That's why many standalone clocks are network cable in & USB out

Your Transport also has their proprietary SUPERLINK connection, which allows a compatible (CEC) DAC to share its clock.