Vandersteen 7 and room treatment

Personally I would start with all the panels in place, as you already know the room.
Then remove panels one by one.

Measurements with REW might be able to show a time domain comb, and keeping the early reflections low is usually better for imaging.

Whatever method you use will be a lot of trial and error, or trial and measurements along with listening.

It could make a good study though.

If it were me, I would remove all the panels and treatment and place the speakers in the listening position to determine what sounds best and then measure after that if you can.  Add the panels back in slowly.  I have become a fan of diffusion rather than absorption since it's been mentioned that you can kill the room when it gets too dead.

So what did I do? Nothing. The Supratek Cortese LCR arrived. It made the Chapmans sound so spectacular that the Vandersteen’s are still sitting on their pallets upstairs for the second week. Maybe later this week. 

 the Vandersteen’s are still sitting on their pallets upstairs for the second week.

Good, let your ears take in the sound, then set up the Vandys. Dollars to donuts, I bet you'll never go back. Be sure to let us know your decision on the Forum.

Bob