Well, Stephen at Audio Consultants advices 5/6 as a minimum to start with, to give some idea on what's possible. Then it can get quite expensive ( ha ) 8/ 10 forI'd love to know what makes DAADs so powerful that only a few are seemingly required to effectively treat a listening room. Or is it perhaps the fact that they're so expensive that users can only afford to buy a few of them? I tried to glean some meaningful information from the manufacturer's website but am not much the wiser, a few details have evidently been lost in translation:
https://www.acusticaapplicata.com/daad.php
example costing around 4.8 - 7 k. There s plenty of explanations on his website. He thinks products from other manufacturers makes the sound a bit "dull ".
But I find the big bass traps from gik suits my tastes, less shrill, more body to vocals and giving a much quieter room.