Acoustics first, EQ second. :)
Contact GIK acoustics for advice. Good acoustic treatment will last while you may change speakers and electronics several times. :) This may also give you better sounding bass, making it easier to listen to great sounding 2-way speakers. This is also my first suggestion. Get great 2-way speaker pair with good bass and good room treatment. This lets you keep your receiver, get great sound and prepare you for upgrading. :)
As for EQ, yes, but you’ll loose the B&W sound. Also, B&W’s tend to measure most neutral around the midrange axis, or lower. Either sit lower or tilt them up in the front. They may also benefit greatly from EQ and phase correction like DEQX or DiracLive alternatives. The diamonds would, but not sure about the Matrix.
Another route is something like the Parasound integrated? Plenty of power, nice built in DAC and I believe subwoofer out. I think Bryston and a couple of other brands have also recently introduced high power integrateds that cost less than a car. Check for subwoofer outputs too.