How do you use the four top boxes? Do you put them as a pair on each side, right next to each other, or are they spaced out more as side delays? I ask as most point source speakers really aren't designed to sit right next to each other, and you end up with more cancellation that you realise, lowering the overall output of the system. Some boxes need almost a 45 degree splay angle between them before you get the effect you're looking for. One company I used to work for had special positioning bars made to go with certain speakers to ensure they were at the right angle. Meyer MSL2 boxes needed to be close to right angles to get about a 60 degree throw with higher power. Experimenting with placement and angles might really help you out and you could be surprised what output you really can get. It may look odd, but it can make a big difference.