[Drixevel]

Not 100% sure if you can block all sounds from playing to a client but what I would try is the sound hooks again but try both setting the volume to 0, changing the path to empty maybe with both of these returning changed and then just flat out returning stop. Certain things like player footsteps are hard to stop because of client predictions from previous experience.

You could send the convar to the client on connect to set their footsteps to 0, I did that once and it seemed to work.