If not the DD67000's - which are really rather much more sonically capable and fleshed out than their smaller siblings, incl. the M2's to my ears - I'd go with actively driven Meyer Sound pro series speakers (Acheron/Studio) and add some big, high efficiency subs.
As a general observation: midrange horn size matters, indeed the bigger they are the less they sound like horns. Modern horn profiles only do so much if they're size restricted (most are), why I'd rather have an older profile horn that maintains directivity control in its entire operating range to make for better coupling with the driver section below.
And let's not forget the importance of sheer displacement below the midrange; dual 15" drivers (or a single or two horn-loaded) do for the vital frequency range they cover what singles can't equal, and so isn't about magic dust or other obscure recipe to accomplish. And when they're high-passed to be relieved of LF-duties and sub-augmented here it only makes them sound better (while adding further headroom) in their upper frequency range.
As a general observation: midrange horn size matters, indeed the bigger they are the less they sound like horns. Modern horn profiles only do so much if they're size restricted (most are), why I'd rather have an older profile horn that maintains directivity control in its entire operating range to make for better coupling with the driver section below.
And let's not forget the importance of sheer displacement below the midrange; dual 15" drivers (or a single or two horn-loaded) do for the vital frequency range they cover what singles can't equal, and so isn't about magic dust or other obscure recipe to accomplish. And when they're high-passed to be relieved of LF-duties and sub-augmented here it only makes them sound better (while adding further headroom) in their upper frequency range.