A 'scope will show the signal is clipping when your turn up the volume too much.

 

A 'scope will show the signal is clipping when your turn up the volume too much.

The circuit seems to work fine at max volume. Its only when I turn it down too far that it stops working.

 

The circuit seems to work fine at max volume. Its only when I turn it down too far that it stops working.

Then the circuit likes the constant amplitude of clipping.

 

Then the circuit likes the constant amplitude of clipping

I don't know if clipping is the issue. The sound bite from post 32 that was computer generated is a square wave. The scope showed the waveform with the corners rounded as usually seen when passing a square wave through analog. All I know is if the level is below 50 mv the comparator will not work.

100%. For some reason, adjusting VLC's volume to around 40% while leaving the PC volume at 100% doesn't work, but putting VLC's volume at 125% and adjusting the PC's volume to 5% does work. Super weird to me.

Not really weird. The comparator requires 50 mv, so the VLC at 40% must be less then 50 mv if the computer is at 100%. The VLC at 125% must be well above 50 mv if the circuit will work when the computer is at 5%. The problem is all these percentage values of level are not relevant when you don't know the actual value.
SG