Mix Position - Diffusion or Cloud

I have an 11' high ceiling ( large roof space above, the ceiling is made of standard ceiling boards with 703 lain on top/inside roof) The inside (interior) of my ceiling is completely un-treated. Would it be better to put some diffusion (auralex t or mini fusors are the most easily available to me in south africa) or Absorption (suspended 703 covered in fabric) above my mix position??? and how far above my head?? maybe a bit of both?? The room is pretty small, 1350 cubic feet, i have diffusion on the back wall and 703 absorbers on the lateral walls and across the corners so far. Still have a lot of work to do. will probably do some more bass trapping on the rear wall soon. Any suggestions Kind regards Tristan Horton Durban South Africa

I'd definitely use absorption overhead in a control room. --Ethan