I have a question about something that is not entirely clear to me.
I’ll get my new Vivaldi DAC next week and will be using it with a Windows 10 Pro PC.
In this PC I installed a JCat Ethernet card and a JCat USB card.
I only use Roon and Fidelizer software on this PC and then USB out to the Vivaldi DAC.
I think this should go well.
But my next step would be to add a Vivaldi Clock.
But now I see in several places that it is very important that the source must have a clock.
Does it actually make sense to use an external Vivaldi Clock with the DAC and a USB source?
With my old Rossini DAC / Clock combination the difference with or without a clock was very noticeable.
The upsampler is no option for me…
In the manual I don’t see an example (drawing) of how to connect such a thing.
A drawing of how the clock cables should run is useful.
Firstly, welcome to the community! 
The key thing to note here is that, as you have read, you need to have the source and DAC locked to the same clock when the source is synchronous, such as when you are using S/PDIF or AES audio from something like a CD transport. Both USB and network audio are asynchronous, so you do not need to try and link your Vivaldi Clock to the computer in any way, just connect the Clock to the DAC.
Just like you found with your Rossini system, there will be very noticeable benefits from having the Clock added to the DAC, even when using USB and Network sources.
While we do not have a drawing for this specific use case, connecting the Clock up to the DAC would be very simple:
- Connect one BNC cable from the Group One outputs of the Vivaldi Clock to Word Clock In 1 on the Vivaldi DAC.
- Connect a second BNC cable from Group Two on the Vivaldi Clock to Word Clock In 2 on the Vivaldi DAC.
There will be a few settings to change on the DAC when you add the Clock, but that is all explained in depth in the Vivaldi DAC manual, and is something your dealer can assist with as well.
Clearly, thanks for the quick answer.