Thank you, downloaded and read!
Unfortunately I cannot get as close to the loudspeaker plane as suggested. All I can do is pull them further apart (they have about 30cm from the side walls) and hope this works.
BTW, what is the change in tonal balance when getting them closer to the side walls? Of course I can experiment myself but I'd rather not move them from the current position: I worked hard to get a nice sound, and even 2cm can make or break the balance.
Have a great weekend,
Costin