Sound in Multiplayer is pretty tricky at the best of times, I know that it is generally accepted that the less noise you use the better, and I think the reason for that is what happens when the map cycles and starts again, I had an ambient_generic in cs_coffee but finally took it out because whenever the game finished and reloaded the generic went mad. I have seen a few articles on this, so If you do manage to get it to work in an MP environment, let us know how it was done.