I checked their web page. The PDF is in German. Here a short translation of the Key Headings:
For over 170 years Boesendorfer is extremly successfull with the study of sound. This sound, caused by strings creates a complex process of resonance in wood. In an ideal scene, a loudspeaker is also such a vibrating body. Boesendorfer has developed a high quailty speaker system which is based on a standard of highest tech and acoustic researches.
If a sensitive perceptiion for a vibrating body comes together with a high musical understanding, it needs more than a scientific approach ...
Since known peakers usually are regulated electronically, use equalizers and are overloaded with frequency separators and sound proofing materials, the Boesendorfers create a balanced, targeted, acoustic activ vibrating, overall sound experience.
THE CORE PIECE
The main ingedient is the patented horn resonator. The emission-area of the sub-woofer system is augmented without inertia and therefore
optimizes the adjustment to the concert room. Only this way, the distortion free and fastest attainable bass will be possible. Another important component is the acoustic active frequency separator. The speakers are specifically constructed and their position is deremined carefully.
Construction and high quality parts are responsible for the pure sound reproduction. They guarantee: full sound, sound spectrum, impuls fedelity, spatial panorama and origin of soundposition. This con usually only experienced in nature or during live events...\"