Clocker value on a network player?

Synchronous signals are one way. The DAC is forced to accept the samples as they come in. With say a CD turner, external DAC’s were forced to accept any incoming timing variations.  The DAC is forced to synchronize with the source.

Asynch uses 2 way communication to allow the DAC to control the sample rates. USB can be asynch. Coax/Optical cannot.

With the exception of USB and Ethernet, all other commonly used digital audio interfaces (spdif, toslink, AES3, i2s) are synchronous. This means that the source (the network player in your case) controls the clock.  

Some DACs will buffer and reclock even these synchronous interfaces, but it's still important to have an accurate and clean source clock to reduce buffer under/overflows and noise. 

Many DACs sound better using one of these synchronous interfaces. For example, my Denafrips Terminator Plus sounds noticably better using i2s than any of the other inputs I've tried including USB. 

I don't believe it makes much difference into a DirectStream.

What about the chord tt?
Asynchronous vs synchronous, another good thing to understand.
usb causes the dac to do its clocking thing without involving the player.  And if dac has good power, this all tends to marginalize the player impact.

Synchronous simply means that the audio data is sent to the DAC at the same rate that it is played (e.g. at 44,100 samples per second in the case of standard Redbook CDs). The DAC has no control over the rate at which the data is sent. 

Asynchronous means that the DAC periodically requests a bunch of audio samples as they are needed and the DAC controls when to do these requests.