Recently saw a post where a person was using the Rossini clock with his Vivaldi. Is this a significant upgrade vs the bare Vivaldi?
This is such an odd combination I doubt that there are too many people with the experience to answer your question.
I do know from other combinations of dCS equipment that Vivaldi clock is a significant element of the result that you achieve in combination with Vivaldi DAC. That is, if you hope that using Rossini clock is a cheaper way of getting the same result, it isn’t.
If the whole idea here is to save on the budget, one option would be to opt for a Mutec Wordclock Clock and a 10MHz reference Clock. the combo MC3+ USB & REF 120 SE paired with the Vivaldi would be an improvement over the Vivaldi alone.
It seems that you have made your mind up then.
I mean an improvement over the Vivaldi DAC alone.
Of course, a Vivaldi Clock added to the DAC is another story … (not tested head to head).