I'm not real familiar with the processing logic found in the 3910 and Denon's other universal players, but the things I would expect would be bass management (which will be ignored if your speakers are set to "large" and your sub to "on" in the 3910's menu) and possibly time delay (if you have set speaker distances in the 3910's menu). You'll know it immediately if there's any surround processing going on for CD's played through the six-channel outputs, if only because you'll get audio from all of the speakers. I know it pretty much smacked me in the face with the S1500 (oddly enough, the effect of PL II on CD's from the S1500 was more pronounced and less appealing than when using the 950's PL II processing for CD playback).