My first reaction is that the room or some other setting is holding back that rather nice sub you're using.
You have tamed that peak nicely and that's for sure why it sounds better, but your low end extension is rather challenged and I don't think it should be if I read
this review of your subwoofer.
Are you using the direct mode and allowing your processor to cross for you? Do you have the subsonic filter too high perhaps on the sub?
What are your thoughts on this?
brucek