EQ will knock down some peaks, but no nulls, that result from standing waves. I say "some" because cutting a peak too far, without regard to delay times, can make the sound worse. Basically, it is location, location, location of the speakers as the cake and EQ as the icing.
I started out using an Emotiva MPS-1 (200 watts x 7 channels) and my bass was loose or non-existant and the mids thin. I had to upgrade my amp. But I still think your issue is 80% speaker location and only 20% other. Keep at it.
