The oomph is not the goal for me, either. The goal is evenness, tightness, naturalness. It's like having a room with two vents for heating/cooling rather than one. It is about distribution of waves, in either case.
Guessing about subs is an infinite project. I suggest a umik and REW and some time spent measuring.
If your subs have adjustable phase, like my Rythmiks, that will help a lot. Sometimes subs need to interact in certain ways to create evenness. Adjustable phase makes that much easier.