The M03 brought my old passive Canton Plus C Subwoofer back to the Orchestra. In passive mode it was ways too bassy to play nicely with my KEF KHT2001 in a small room (~12qm²). Together with the Fosi M03 (and a small modification: I removed the crossover and soldered the 2 coils of the woofer in serial so it has 8 Ohm) Bass is now extened to 30 Hz (measured with Umik Mic and REW) and fills nicely the absent bass and upper bass. Highly recommended for that purpose.











