I’m with @frogman. My first audition of the Magneplanar Tympani T-I (three panels per side) in 1973 included Boult’s version of Holst’s The Planets on EMI. Never before had I heard the full depth of the orchestra reproduced: the percussion section sounded further away than the wall behind the Maggies, and raised above the rest of the instruments (the section is often on risers). When I opened my eyes at the end of Jupiter, I was actually startled!
Large panels also reproduce the size of a grand piano, pipe organ, drumset, upright bass, and other large instruments like no box speaker I have ever heard. And singers mouths are reproduced at a lifelike height. Almost all box speakers make music sound miniaturized to me, like the figures and furniture in a doll house. And, like the music is coming from two bricks removed from a wall separating the performers from myself. Panels sound like the wall has been torn down. Wide open, free from any and all physical restraints.