If the left and right speakers are set to "small," the 990 will apply bass management and steer data below the specified crossover point to the subwoofer - this will be true whether you are listening to music or watching a movie. Since I'm off to dinner, I'll quickly offer a couple bass management summaries (one here in my 990 review and another here - complete with signal diagram - in my 990 firmware notes) that may help with some of the details. The bass management is pretty powerful, so if you have questions just toss them out and somebody around here will help sort it out.