I always thought the Term musical sounding referred to the extra harmonic goodies and irregularities that give the speaker a characteristic sound.
The term musical is often used to describe Guitar and bass guitar speakers and cabs.
The term Accurate is normally used to describe reference audio.
From what I've read about Open backed Horns (and maybe scoops too), there is an uneven load on the driver in the negative stroke so there is an amplitude distortion issue much like the squares law distortion of J-Fet transfer curves.
But this type of waveform more closely resembles that of a stringed instrument (Larger + swing than -).
I guess the only way to know for sure is to look at what happens to a sine wave fed into the thing.
I guess its related to the same type of voodoo musicality that dipole (Open Back) speaker have for some people.
I'm guessing this mainly applies to acoustic music reproduction, as acoustic instruments are 3 dimensional entities that radiate portions of their energy in multiple directions (At least ones with resonant bodies). And have a complex interaction with their environment.
Sealed Horns, and speaker cabinets. By nature and Design focus their energy (unless the enclosures are quite live) in one direction. By nature they can not sound just like an acoustic instrument.
By having the rear wave reflecting off other surfaces I think perhaps it can help trick the ear into thinking the sound from the speaker has more depth and realism.
I think even Siegfried Linkwitz mentions on his site that dipole speakers need to be a certain distance away from walls to work their magic properly. I wonder if this the case with the Bassmaxx subs.
I haven't actually heard the things so I can't give any subjective feedback on them.
Antone-