You should have section to select digital, analog, or auto...Auto would select whatever format is being processed.
Aside from that I would check your dvd player to make sure you are not set to PCM...If so your pre would always detect analog signal and therefor default to Pro Logic...
Aside from that I would check your dvd player to make sure you are not set to PCM...If so your pre would always detect analog signal and therefor default to Pro Logic...