Stop and restart pulseaudio to apply your changes by executing these two commands:
pulseaudio -k pulseaudio -D
If you get an error on the second command you probably can ignore it. At least in my case the daemon was restarted although I got some error.
And here is what the configuration variables do:
Enabling the variable „remixing-use-all-sink-channels“ has the same effect as enabling „Speaker Fill“ on Windows.
Enabling the variable „enable-lfe-remixing“ has the same effect as enabling „Bass Management“ on Windows.
Assigning a value different from 0 to „lfe-crossover-freq“ lets you specify the proper crossover frequency recommended for your subwoofer. So you should probably NOT use 150 Hz as I did in the example above and instead use a value that is recommended by your subwoofer manufacturer!