No secure info but when we were there it was stupidly quiet and the only place that was going for it was right at the front by the dj booth.
You could easily hold a conversation on the steps at the back of the dance floor and at the front bar you could hardly hear anything.
The reason I think this is due to regulations is that every five mins I could see the promotor in a state adjusting the mixer levels....before each dj came on you could see him briefing them so I think they must have been warned or something.
The sound level creeped up and was back to normal in the evening though, and knowing about the 'hasta manana' attitude of the Spanish, I shouldn't think this rule will last very long!
Also it's just from one Sunday and so far I am the only person to bring it up on this board, don't worry too much.