I’ve considered using the Mixer, and looked at using the Silence template, but both are too involved (from Write mode) to be a useful alternative to Alt+S.
Whatever method is used, it has to be effected by a single key command or click, within the Write mode window.
The idea is to be able to switch from Dorico’s sound to a different sound source while leaving one’s project open, in Write mode – and then switch back. This is required in teaching situations, as well as many other scenarios.
Of course, another very simple approach would be to make the Dorico project activate button into a toggle, between activate-deactivate (which is how its used in your parent company’s Cubase), but this, from what I’ve read, is still in the future.