Dim and Muting speakers

I'm assuming you're trying to mute and dim the output of your Mac. if you're trying to mute and dim your interface you'd have to look into your interface's software.

This should dim your system volume (if you change the volume while dimmed, change the volume then un-dim the volume will return to the original volume before dimming)

//dim percentage below is relative to whatever your current volume is
// in this case the volume will be 77 percent of the current volume
const dimPercentage = 77
function getSystemVolume() {
    return Math.round(+sf.system.execAppleScript({
        script: 'get volume settings'
    })["Result"].split(",")[0].split(":")[1]);
}
function dimSystemVolume() {

    let newSystemVolume
    if (!globalState.prevSystemVol) globalState.prevSystemVol = getSystemVolume();
    if (!globalState.isSysVolumeDimmed) {
        newSystemVolume = globalState.prevSystemVol * (dimPercentage/100);
        globalState.dimmedVolume = newSystemVolume;
        globalState.isSysVolumeDimmed = true
        log ("Dimmed")
    } else {
        newSystemVolume = globalState.prevSystemVol;
        globalState.isSysVolumeDimmed = false
        delete globalState.prevSystemVol
        log ("Un- Dimmed")
    }
    sf.system.execAppleScript({
        script: `set volume output volume ${Math.round(newSystemVolume)}`
    });
}


dimSystemVolume()

This will toggle the system volume between mute and un-muted:

function toggleSystemAudioMute() {
    sf.system.execAppleScript({
        script: `set curVolume to get volume settings
if output muted of curVolume is false then
	set volume with output muted
else
	set volume without output muted
end if`,
    });
}

toggleSystemAudioMute()