You are correct, no paint or wallpaper, which means that the finish quality of the drywall is not that important. Instead the walls and ceiling will be treated with DYI acoustic panels covered in cloth. The front will be the live end, i.e. only slighty absorbant. The sides will be most absorbant, and the rear of the room will be in between the two, but also include some items to add diffraction. The ceiling will be covered with DYI acoustic tiles similiar to the ones discussed in this thread:
Fabric FramesDepending how things sound, I may also build bass traps hidden behind the sides of the "stage". While I am not 100% decided on all of the details of these room treatments, I am getting closer to finalizing my plans.
Rob