Hi Till E.I'm running Pi 7's at home and have a weak mid/treble.
I figure it's because I'm not using a standard horn on the tweeter. Are you using standard components all over, or are there some places where you've "optimized" things? (not that any of us would ever do something like that... ;->)
In my case I'm looking to back towards the "normal" horns soon.
Grant.