Canton's DC Tecnology

[stereotek]

"DC technology ('Displacement Control'), developed by Canton prevents the uncontrolled deflection of the bass loudspeaker membrane at low tones. It suppresses the subsonic (i.e. not audible) oscillations and allows the bass tones to sound perceptibly sharper and more precise."

Here's an old review from 2006 of the Reference 1 from Stereophile:

Further deep-bass response is boosted by Canton's Displacement Control (DC) technology, essentially a high-pass filter that eliminates the harmonics of infrasonic frequencies that the drivers can't produce but that generate high levels of distortion. Canton claims that the DC technology can "decrease the lower cut-off frequency of the drivers by as much as a full octave."

Canton Vento Reference 1 DC loudspeaker | Stereophile.com