aplay -Dhw:0 --dump-hw-params anystereo.wav
should show channel max is 4 when you need software low pass filter but only 2 wheb your laptop have hardware low pass filter
aplay -Dhw:0 --dump-hw-params anystereo.wav
should show channel max is 4 when you need software low pass filter but only 2 wheb your laptop have hardware low pass filter