Hi
I had a switch to enable / disable mixer in playback options
This is not perfect, and you may to restart volumio to fully apply … But this is working 
I mis something, but for a first attempt not so bad
I had a description in /volumio/app/i18n/strings_xx.json to fit with my own langauge
Modify /volumio/app/plugins/audio_interface/alsa_controller/UIConfig.json
add "enable_volume in
{
“id”: “volume_options”,
“element”: “section”,
“label”: “TRANSLATE.PLAYBACK_OPTIONS.VOLUME_OPTIONS”,
“icon”: “fa-volume-up”,
“onSave”: {“type”:“controller”, “endpoint”:“audio_interface/alsa_controller”, “method”:“saveVolumeOptions”},
“saveButton”: {
“label”: “TRANSLATE.COMMON.SAVE”,
“data”: [
“mixer_type”,
“mixer”,
“volumestart”,
“volumemax”,
“volumesteps”,
“volumecurvemode” ,
“enable_volume”
add
"visibleIf": {
"field": "enable_volume",
"value": true
},
,
for each field of volume option
add the swith at the end of volume option
{
“id”: “enable_volume”,
“element”: “switch”,
“doc”: “Enable or disable Volume control”,
“label”: “TRANSLATE.PLAYBACK_OPTIONS.VOLUME_ENABLE”,
“value”: true
}
modify /volumio/app/plugins/audio_interface/alsa_controller/ndex.js
in ControllerAlsa.prototype.saveVolumeOptions add :
self.setConfigParam({key: ‘volumesteps’, value: data.volumesteps.value});
if (data.enable_volume) {
// this.logger.info(‘Enable value : true’);
}
else {
//this.logger.info(‘Enable value : False’);
data.mixer_type.value = ‘None’;
this.logger.info('mixre typ : ’ + data.mixer_type.value);
}
if (data.mixer_type.value === ‘Hardware’) {
self.setConfigParam({key: ‘mixer’, value: data.mixer.value});
} else if (data.mixer_type.value === ‘Software’) {
var outdevice = self.config.get(‘outputdevice’);
self.enableSoftMixer(outdevice);
} else if (data.mixer_type.value === ‘None’){
self.setConfigParam({key: ‘mixer’, value: ‘’});
var outdevice = self.config.get(‘outputdevice’);
this.logger.info("Output device : "+ outdevice);
this.logger.info(‘softvolumenomber :’ + self.config.get(‘softvolumenumber’));
//if (outdevice == undefined){
var outdevice = self.config.get(‘softvolumenumber’);
if (outdevice == undefined){
outdevice = 0;
}
//}
self.commandRouter.sharedVars.set(‘alsa.outputdevice’, outdevice);
modifiy in ControllerAlsa.prototype.getUIConfig
if (activemixer_type === 'None') {
self.configManager.pushUIConfigParam(uiconf, 'sections[2].content[0].options', {
value: 'None',
label: self.commandRouter.getI18nString('COMMON.NONE')
});
self.configManager.pushUIConfigParam(uiconf, 'sections[2].content[0].options', {
value: 'Hardware',
label: 'Hardware'
});
self.configManager.pushUIConfigParam(uiconf, 'sections[2].content[0].options', {
value: 'Software',
label: 'Software'
});
self.configManager.setUIConfigParam(uiconf, 'sections[2].content[0].value', {
value: 'None',
label: self.commandRouter.getI18nString('COMMON.NONE')
});
[b] self.configManager.setUIConfigParam(uiconf, 'sections[2].content[6].value', {
value: false
})[/b];
Could be more elegant and efficient … But Works… And even if i have to restart volumio … I don’t change this parameter every days
Could be better
When rectivated mixer => You have to chose hardaware or software, save and chose the name of Mixer
Save button actio not alwaay clear at screen (in logfiles this is fine)
Add all languages
…
if can help somebody provide my index.js as sample
Regrads