Electron + Angular: switch microphone while recording

I'm struggling to change microphone while recording a window through desktopCapturer.My recorder process is basically a hidden BrowserWindow running an Angular service, and I initialize my service this way:

init(): void {
    //get "Preview" window
    from(this.electron.desktopCapturer.getSources({ types: ["window"] }))
      .pipe(
        //transform capturer source in media constraints
        map((sources) => {
          return {
            audio: false,
            video: {
              mandatory: {
                chromeMediaSource: "desktop",
                chromeMediaSourceId: sources.filter(
                  (source) => source.name === "Preview"
                )[0].id,
              },
            },
          };
        }),
        switchMap((constraints) => {
          // Forced to cast to "any" as chromeMediaSource and chromeMediaSourceId are not standard WebRTC constraints
          return zip(
            from(
              navigator.mediaDevices.getUserMedia({ video: false, audio: true })
            ),
            from(
              (<any>navigator.mediaDevices).getUserMedia(constraints)
            ) as Observable<MediaStream>
          );
        }),
        switchMap(([audioStream, videoStream]) => {
          videoStream.addTrack(audioStream.getAudioTracks()[0]);
          return of(videoStream);
        }),
        take(1)
      )
      .subscribe((stream) => {
        // get stream from Preview window and creates recorder
        this.audioCtx.createMediaStreamSource(stream);
        const finalStream=this.audioCtx.createMediaStreamDestination();
        this.recorder = new MediaRecorder(stream, {
          mimeType: "video/webm;codecs=h264",
          videoBitsPerSecond: 3 * 1024 * 1024,
        });
        this.recorder.ondataavailable = (e) => {
          //recording stuff
        };
      });

When the window receives a message informing that the audio source has changed, this is what I call:

this.avService.audioSource.subscribe(audioSrc=>{
  if(this.currentMic){
    this.currentMic.disconnect();
  }
  this.currentMic=this.audioCtx.createMediaStreamSource(audioSrc);
  this.currentMic.connect(this.audioCtx.destination);
});

The only effect I get is to hear an echo while recording, but it always takes the default microphone in the recorded video.

How can I solve it?