I use the offset as I like my bass a few dB hot for movies, so I use the offset to back it off for music. The offset feature works really well and is a big plus to have. As far as I know using "Upsample" or "Stereo" mode, if you set the speakers to large and the crossover to the lowest frequency (40Hz) you do not get the sub. However, in this configuration my fronts (Klipsch RF-25s) are too anemic and do not produce enough bass for 2-channel music. "Bypass" mode seems to kill the sub for me no matter what the crossover settings are at.