Hi Miranda, As far as I know only Croatian performers in the old town this year: traditional acapella music, groups Teatar and Da Riva and Milo Hrnic who is a Croatian folk singer.. Will keep you posted if I find out anything new...
One more thing - traditionaly parties (techno, house) called The Gate are happening for new year in Lazareti which is right next to the old town.. I hear SILICONE SOUL is playing this NY..
If it's any help I was there last year and it was amazing - thousands of people on the street like there usually is in Edinburgh - it was gorgeous to be in the old town with all the people on the streets. Seems there aren't too many actual events this yer though which is a shame.