>the issue you are having with the LM324's output stage is probablly
>crossover distortion as the output stage switches between sourcing
>and sinking current. you can eliminate this by putting a resistor
>to the negative supply rail so that no matter what the output
>voltage it is always sourcing current.

I first came across this problem when attempting to use a 741 as a headphone 
amplifier, about 30 years ago. A 1k resistor from output to negative supply 
fixed it. 

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