[infinitesymphony]

That should be an optional setting on your receiver. For example, setting speakers to "Small" routes frequencies below the crossover to the sub, while the "Large" setting routes all frequencies to the mains. If all speakers are set to "Large," only the .1 LFE tracks in movies will be routed to the sub, unless you set the preamp to "Subwoofer Plus," which will route all frequencies below the crossover to your sub, even with two-channel music.

Edit: Also, 200 Hz is much too high for a crossover; are you sure it's 200 Hz? If so, you should still be able to hook into your subwoofer's adjustable crossover input. Frequencies above 100 Hz or so can be localized, which could potentially collapse your stereo image, since some of the lower-mids will appear to be coming from the subwoofer. 80 Hz and lower is recommended, especially if your mains can handle frequencies around that point without roll-off.