Placement, Placement, biggest real way to gain or lose low freq. Try them 3 ft out from the backwall and then 1 ft, etc... and everything inbetween will be more bass punch but more smooth soundstage etc... So go as far into the room as possible and increment back toward the wall in small movement until it snaps in where you like it, but this may also need to move in and out from the side walls as well to re-focus soundstage.. Also, Try the side fireing in toward each other and fireing out toward the walls, I would guess they are a mirror pair. Welcome to the tedious and rewarding world of speaker placement, its tuff and I have been thru weeks without settling on new speaker placement but it will find a spot at some point.
A lot of the time I would listen to something not bass driven and thought it is great but then put in something I know needs more and they gotta be moved back an inch or so to gain bass from the backwall, find the best medium.