With the changes to the Headsets with the new DS9 Featured Event, I thought it would make a great combination with the MACO Armor. And in the process I discovered my Joined Trill cannot use headsets.
I don't think Joined Trill (or trill at all, but I'll be honest and never made a regular trill or tried it on a BOFF) can use headsets. I have no idea why, but it's been that way since the beginning IIRC. And yeah, it's annoying.