I own a ZZ8 with the updated DAC, version 2007; it resides in my home, in my studio is a Wadia S7i.
the Wadia is indeed "better" in the sense of space and grip of a pianos initial sound pronounciation - but to be honest: both are really great, and the ZZ8 is not only great sounding, but a design classic. I will not ever want to get rid of it, and hope for a long life..
The USB DAC by Lars Moltke is probably very interesting, but it will have to compete with Ayre and the usual suspects, let alone PD who have asserted themselfs in the highest bandwidth, as opposed to Wadia who seem to tread carefully by Avoiding number-dropping adverts in favour of gorgeous sound! FWIW..