I use 6 KODAK - Ektapro - 9010 - slide projectors and 1 Rollei P66 medium format slide projector.
All are computer-controlled by the software m.objects. (see also http://www.mobjects.de )
Sound is digital.
The screen measures 1,80 m by 5,40 m. The screen is variable, up to 3 pictures can be shown simultaneously. But there are also panoramic images which fill the complete screen with only one picture.
Commentary is live.