The Blackmagic Television Studio HD provide a talkback option but via an aviation standard jack which is .206″ 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 (microphone) jack which I thought was the one on the right.
PJ-068 or 0.206 inch jack for aviation microphone.
Tip is for PTT (not used by ATEM TVS HD)
Sleve – Mic Hot
Body – Mic cold (Gnd)
Type = Dynamic (no power required to operate) Dynamic mic is like a speaker in reverse, air pressure moves the coil past a magnet which produces a small current. Requires an amplifier and it is very easy to introduce hum into the signal if the amplifier does not have clean power.
Aviation headphone standard is mono, TRS ¼ inch although ATEM TVS DH seems to be stereo capable and works with standard stereo headphone.
Looking at the photo in https://www.ebay.com/itm/UFQ-Aviation-headset-Airbus-XLR-to-GA-Dual-Plug-Pilot-Headset-Adapter-/272408976292
you might think the one on the left is for stereo headset but this is the 0.206 microphone jack
When using a Clearcom/RTS type headset, the microphone level is to low. I have built a circuit based on http://darrenyates.com.au/electronics/archives/16 with an XLR 5pin (for the adapter above) and 4 pin socket (for the headset).
Warning: Run off 9v battery, or if you want to run a dirty plug pack, use a 317 regulator with good filtering, otherwise you get lots of hummmmmmm.