I just got in these Central Soundz Wireless Whispers headphones for the XP Deus‘ WS4 puck. There might even be the word Quantum in the name. Sheesh that’s a long name. There are a few 3rd party headphones that accept the WS4 puck. These include the Grey Ghosts, Vance Muffs, Chef Phones (from England) and now these are by far the winner in both comfort and in matching the tones of XP’s headphones. I got these from Andy Sabisch, so for now contact him for a pair.