Asus Xonar Essence STX - Manual (Page 37)

32 ASUS Xonar Essence STX
4 LFE Crossover
Frequency
Adjusts the cut-off frequency (20~250Hz) for LFE (low-
frequency effects) signals. Xonar Essence STX will filter out
the bass signals below the crossover frequency from small
speaker channels and forward them to the subwoofer. The
higher the crossover frequency, the more bass signals will be
subtracted.