If you want straight DD or DTS (depending on what you source is sending), just hit the "Dolby" or "DTS" button to scroll through the appropriate options. The first time you hit *any* of the "mode" buttons ("Dolby", "DTS" or "Stereo") it will display on the front panel the current processing mode.

Usually, if I send the 990 a DD signal, it is forced into DD processing, and no PLIIx, etc.