Bass nulls and bass booms are caused by room nodes. These are created by the shape of your room and the position of your speakers within that room. Changing speakers will do nothing. Room treatments will not help a great deal as bass nodes require fundamental changes in the room shape to be dealt with. Bass boom can be solved by DSP but bass nulls, as you have, cannot, as it is not good practice to boost frequencies a lot with DSP as it can lead to clipping. However, you could try supplementing the bass with subs. Oh, I’m sure you have done this, but check the previous owner did not leave any foam plugs in the ports - B&W supply these to help temper bass boom issues and they are often left in there when selling. Alternatively can you fire your speakers down the room the other way and move the listening position ? That will fundamentally alter the bass nodes
With regard to your other issue of too much glare in the top end, unlike bass issues these are easy to treat with room tweaks: rugs, curtains, simple absorber panels at reflection points etc.