The Blackmagic Television Studio HD provide a talkback option but via an aviation standard jack which is 2.06″ rather than the 1/4″ jack used for headphones.
I have 4 or 5 pin XLR headsets so ordered ths adapter from eBay (China).
Update: It arrived. quality is good but headset jack is mono only. From the picture it is hard to tell which is the smaller (microsophone) jack which I thought was the one on the right.