https://www.rythmikaudio.com/DirectServo.html https://www.rythmikaudio.com/DirectServo.html Seems like they do the same in their subs what Backes & Müller and

https://www.rythmikaudio.com/DirectServo.html https://www.rythmikaudio.com/DirectServo.html Seems like they do the same in their subs what Backes & Müller and Silbersand do for every speaker. Cinema for the ears, if you ask me. Even at volumes below speech, you can hear EVERYTHING! Even low bass, from a closed enclosure!