The computer speakers crackle and give distorted sound at high volumes in Linux Mint 20 XFCE. To overcome this, open a terminal window and enter the following commands:
Use the right arrow key to locate the option for Auto-Mute. It will show enabled. Change it to disabled by pressing the down arrow key and Esc to exit alsamixer.
Secondly, enter the following command:
sudo apt-get install libasound2-plugins-extra <enter>
Lastly, if above do not work, enter following command:
pulseaudio -k <enter>
The crackling or distortion is almost gone.