My advice is please wait until you can have someone, like me!, come over and do some setup and tweaking. You have an unbelievably capable setup. You should not be lacking at any fq. The setup and calibration makes all the difference!
Also, your room being open has a greater effect on lower frequencies then midbass. So you having lots of low end shows me your room isn’t the main cause of missing midbass. The calibration and setup must be the biggest issue.
You built a hell of a speaker setup, but I have learned these things are far from plug and play.
I will definitely wait but at least I know now there is a dev that could fit in my space if the calibration can’t get there.
Sent from my iPhone using Tapatalk