I think you don't know much about the Quad ESL.There is one treble panel in the centre of each ESL 57,flanked by a bass panel to either side. Three panels per speaker only.
So when you stack you get 2 treble panels and four bass panels per stack.You get more of the bass into the room this way and the result is you do not feel the need to add on subwoofers,neither do you need a super tweeter.When you add the subs and super tweeters you change the sound of the Quads and move into territory that is frought with problems,beaming tweeters, booming bass.Talk about room node problems. Doubling up on Quads or doubling up on CLS is not meant to change anything about the sound of either speaker, and I have never claimed it would.It is all about delivering more of the sound you liked about the speaker in the first place.
So when you stack you get 2 treble panels and four bass panels per stack.You get more of the bass into the room this way and the result is you do not feel the need to add on subwoofers,neither do you need a super tweeter.When you add the subs and super tweeters you change the sound of the Quads and move into territory that is frought with problems,beaming tweeters, booming bass.Talk about room node problems. Doubling up on Quads or doubling up on CLS is not meant to change anything about the sound of either speaker, and I have never claimed it would.It is all about delivering more of the sound you liked about the speaker in the first place.