GSG, i know, but when i describe this i prefer to use human language because not everyone will understand frequencies talk.
like i mentioned ASG2 is more mid centric IEM, it has good bite to mid bass but lower or sub bass is missing a bit. trebles tuning down aims to avoid affecting the mid range clarity which otherwise can be compromised if upper mid range is tuned up. what happens to ASG2 is because of mid centric tuning low bass becomes compromised a bit and drop in upper mid range shrinks the stage a bit. i believe describing this like this is easier than going into frequency range numbers. ASG2 mid centric presentation tuning displays common problem you have in many floorstanding loudspeakers, this is why some hard core audiophiles prefer often standmount loudspeakers to floorstanders.