Take a good sniper rifle, take out all alarm panels at the bottom of the big speakers. Use the camera to mark all enemies, ignore all heavies till last take out all other enemies. then if you have heavy take down get in nice and close and take them down, If not one C4 takes down a heavy.
Rinse and repeat. Each one can net you 1500xp for doing so undected, 550 for no alarm trigger, 500 for take over