i also suspect that you hear the side with the delay as quieter, because our brains use micro delays to perceive directionality along with volume (haas effect). one side is delayed slightly, so the brain thinks it's further away and so must be quieter than the other side. it's worth checking with a level meter whether there really is a volume difference between the two sides, or it's your brain fooling you. i just tested it and found a difference of about 0.2db between the dry side and the delayed side. the question is then, do you adjust like michael did, so that you perceive both sides as equal, or not.