As an addendum to my above comments about the spacing of planars from the wall behind them, 5’ or more is no guarantee that the resulting sound will be good. In 2018 I attended the U.S.A. premiere of the new Magneplanar MG30.7 at a retail location (Echo Audio in Portland Oregon), with Wendell Diller himself having set up the speakers. The 30.7’s were quite a distance from the wall behind them---about 8’, though the bass panels were only a foot or so from the side walls. The sound was surprisingly disappointing to me (I own Tympani T-IVa’s, of which the 30.7 is a reinvention).
I don’t want to say any more about the sound, as the digital-only source material (streamed?) was accessed from a handheld remote controlled by the shop owner, almost all of it previously unheard by myself. The electronics were also unknown to me, and the room itself was completely untreated---absolutely no acoustic treatment. The room was constructed of what appeared to be cement, all the walls bare and very reflective, including of course those behind the speakers. Ridiculous!