SB_DSP_PLAYBACK_FILT
mixreg = snd_sbmixer_read(chip, SB_DSP_PLAYBACK_FILT);
snd_sbmixer_write(chip, SB_DSP_PLAYBACK_FILT, mixreg | 0x20);
SB_SINGLE("PCM Playback Filter", SB_DSP_PLAYBACK_FILT, 5, 1),
SB_DSP_PLAYBACK_FILT,