<form [formGroup]="musicForm" (ngSubmit)="submit()">
  <label>
    <input type="checkbox" formControlName="selectAll">
    Select/Unselect all
  </label>
  <label formArrayName="musicPreferences" *ngFor="let genre of musicForm.controls['musicPreferences'].controls; let i = index">
    <input type="checkbox" [formControlName]="i">
    {{musicPreferences[i].genre}}
  </label>

  <button>submit</button>
</form>