The eye-catcher is, of course, the large, mathematically precisely calculated, spherical midrange horn, which rests on a tube. This, as well as its tweeter counterpart and the vertical trim panels of the bass cabinet. A midrange driver with a "Soft Mesh" membrane sits behind the 37-centimeter-long horn, made from the amorphous polymer ABS. Its voice coil runs in the stable field of an "AlNiCo" magnet, an alloy of iron with aluminum, nickel, cobalt, copper and in this case titanium, to which special audiophile qualities have been attributed by high-end enthusiasts.

The funnel for the tweeter, only 18 cm in diameter, is also made of ABS. In this tweeter, a thin, lightweight "Mylar" film does the work, whose motor is a flat ferrite magnet. You can see it when you unscrew the horn, attached via a thread. The narrow cloth cover in the center of the woofer can afterwards be removed, and you immediately see the two big bass drivers right behind it. These are not powered by the main amplifier. Rather, they are powered by a 1000-watt active module, which consists of two effective switching output stages of 500 watts peak power each.

This is controlled by the DSP-based command station, which normally draws its musical information from the main signal, digitizes it and, if desired, processes it in many parameters, converts it again and feeds it to the Class D amps. For this purpose, the listener can call up fixed presets via a small display on the back of the speaker, for example to set the woofer three or six decibels louder or quieter. In the same way, the transmission range of the bass speaker, which extends from about 20 to 200 Hertz and has its upper cutoff frequency at 170 Hz, can be extended or reduced by 30 Hz, which has direct consequences for the homogeneity of voices and instruments.

More interesting, because it is much more complex, sensitive and effective, are the various possibilities the control menu offers. This includes correction curves that exactly match your "playground" and result from a complex measurement procedure in the listening room (see side). With this extensively elaborated tool, Avantgarde Acoustic consistently uses the advantages of active speakers to the improvement of sound quality.

Now for something curious: Even pieces of music with a supposedly rather low amount of low-frequency content sounded considerably more agile, shadier and more relaxed, especially in the mids and highs – thanks to the compensation, which only reaches up to a maximum of 300 Hertz due to the principle.
Thanks to the extreme efficiency in conjunction with unusually high impedance, any amplifier, no matter how powerful, could play mostly "unloaded" on the Duo XD, which at 10 watts are louder than normal boxes with 1,000.