For the Ciunas, I don't know how the converter has changed from the JKDAC model, but I suspect he made some changes that parallel those in the Dac. As for the later, three days in I'm finding it's really good. For some pre-production reviews, check the thread at the link below. One thing to note is the prices are in Euros, so if you're in the States deduct about 20%. John answers emails promptly and is very helpful.
http://www.tirnahifi.org/forum/viewtopic.php?f=8&t=2079
http://www.tirnahifi.org/forum/viewtopic.php?f=8&t=2079