The point of turning off sound is to... remove the sound.... Just turn the sound back on after the game begins :)
sound no matter what

I think you would like the option to turn on/off particular sounds instead of having to turn on/off all sounds at once. This is an interface feature that I would expect to be added at some point. It would even be nice if the user could specify custom sounds for each event.
But, I think the development team is busy tackling big issues like disconnects and the like. The finer enhancements will probably have to wait.
In the meantime, thesexyknight might have provided a workable solution. Can you turn sounds off during games and back on in between games?
Even when I have sounds turned off during live chess, I would still like to hear a "start of game notification." Sometimes I create a seek, then go to another browser while waiting for it to be accepted. (My seeks take a while to be accepted because I seek slow time control games.) When the pairing is created, I would like to hear a sound to alert me that the game is ready.