Hi Reubent,
Since my wife is watching TV right now, I'll check the Pioneer DVD player later to see if there is a Stereo mode. Regarding the PCM, I believe that there won't be signal sent to the subwoofer via the optical audio. Whenever I watch or listen concert DVD in PCM mode, I don't hear much thumb thumb, and when I look in the back of the subwoofer, the red led light never turns green as it does not detect any subwoofer signal, unless the signal in PCM is really weak compared to the 5.1 format. Twirling my thumb... oh boy oh boy. heh heh heh. Crying in tears... but thank you any how.