That amp and those speakers look amazing. Which DAC is best is going to depend on the exact tonal profile of the piegas. Assuming that is a typical ribbon (and is nor terribly bright) my hunch is the Dave and MScaler combo would be the slightly better choice. That being said, I also assume that the amp is not fully balanced. The single ended version of the Rockna Wavedream Signature lists for $11K and may be just as good for less money.
You could add the Rockna Wavedream (with Rockna) server or a K30 from Antipodes (with the Dave) and have and insanely good digital system that will give you every drop of clarity available from your new amp and speakers.
I am not running ribbons here at the moment but am running Art Audio Opus 4s which little KT88 based monos. You and I might have similar taste.
You could add the Rockna Wavedream (with Rockna) server or a K30 from Antipodes (with the Dave) and have and insanely good digital system that will give you every drop of clarity available from your new amp and speakers.
I am not running ribbons here at the moment but am running Art Audio Opus 4s which little KT88 based monos. You and I might have similar taste.