Technics SB-7000 Bass Upgrade

I ended up stuffing the boxes with some moving blanket and kids toy stuffing. The bass is pretty dialled in now. I have however lost some of the lower midrange.

I imagine there’s a lot to speaker stuffing but can anyone recommend some simple rules to follow in terms of materials, extent of stuffing to antenuaye the lower frequencies but not lose out on the lower midrange. Or is it just a question of trial and error.
 
I ended up stuffing the boxes with some moving blanket and kids toy stuffing. The bass is pretty dialled in now. I have however lost some of the lower midrange.

I imagine there’s a lot to speaker stuffing but can anyone recommend some simple rules to follow in terms of materials, extent of stuffing to antenuaye the lower frequencies but not lose out on the lower midrange. Or is it just a question of trial and error.

Low density mineral wool is a very good material to use inside a speaker box