Reviews, reviews, reviews...

Question: How to remedy only intermittant sound from subwoofer?

I have the Klipsch KSW-10 connected via a y connector to my Sony Dolby 7.1 receiver. The subwoofer only kicks in where there is extreme output to the SW channel (usually some sort of explosion), then works beautifully until the end of the movie, when it cuts out again. Most of the time, there isn't good output, as not many movies have the sort of output that's needed to get it to kick in. Any thoughts?