Hi, Martin
Actually, DOP is a part of the Artist version of Cubase (Cubase Artist 13.0.20 Operation Manual, p. 435), contrarily to what the Cubase versions comparison chart states, but it’s a cut down version, which is rather uneasy to use, apparently. There has been a recent thread, on the subject :
Can´t process audio in Direct Audio processing - Cubase - Steinberg Forums