Do you have anything else to say than "You can't enable sound with libctru cause it doesn't have any API to do this."?
You said this in all the other posts. and it's getting pretty repetitive.
But it's true.
The DSP bins and the DSP itself are not fully RE'd so that means no API (if there will ever be one that is. Maybe people will have to include a custom DSP bin, then use it through the service)