PCIe NIC with ROCK (MOCK)

Tinkering
21

With a typical DAC implementation, toslink would incur higher jitter.

22

thanks peter - an LPS is next up on the upgrade/tweak list.

lumin products are the certainly gold standard by a wide margin and were the inspiration for my MOCK and fiber projects. the lumin x1 is a fantastic piece to aspire to. over time i hope to see other lumin products include an SFP port.

1 Like
23

even with DACs that have their own internal clocks which given a digital stream of sufficient quality will take over?

24

That’s still implementation dependent. Unlike asynchronous USB audio, S/PDIF embeds the clock in the signal and by design the DAC is slaved to the signal. Toslink conversion introduces even more jitter so traditionally audiophiles preferred coaxial to toslink. Some DAC try to reclock that signal, but it is unclear to me how successful it can be if your source is the PC on-board S/PDIF output. Some DAC may do it better than others.

25

thanks for the explanation!!

when using the optical s/pdif input on my DAC (t+a dac 8 dsd) the internal clock symbol illuminates, thereby, indicating it has been able to switch over from the source to the internal clock.

interestingly, in a prior system configuration using an airPlay enabled device connected via toslink, the DAC’s internal clock symbol did not illuminate. however, when apple introduced airPlay2 with improved routines the DAC’s internal clock symbol then illuminated. this indicated the source clock signal quality was now sufficient for the t+a clock to take over.

26

I suggest you do these experiments:

  1. With fiber input to MOCK, compare MOCK USB audio output vs MOCK toslink output (with USB cable physically disconnected) to your DAC, using 16/44.1 music sent as lossless (non-upsampled) to your DAC. See which sounds better to you. If your S/PDIF reclocking is “perfect”, it should sound better than USB due to isolation. However, if we accept that perfection cannot be achieved in practice, then USB may sound better.

  2. Especially if you find toslink to sound better, you can proceed to compare fiber input vs copper Ethernet again with toslink output, since you previously did that comparison using USB audio output instead of toslink. (Since toslink is perfectly isolated, if your DAC is perfectly immune to toslink jitter, then fiber vs copper Ethernet should not matter in theory.)