The behaviour of the output filter is directly dependent on the connected load. The key figure for this is the nominal impedance of the loudspeaker. Because there are known different types here – usually between 4 and 8 ohms – an adjustment to the speaker impedance can be switched on the back of the device. This individual adjustment linearizes the time response of the filter in particular.
By the way, this dependence is an inherent feature of every PWM amplifier. However, as far as we know, we are the only manufacturer who addresses this issue and offers a solution. It may sound quite good on average, even without this adjustment. However, on average quite good is not a goal for us. For really coherent music transmission, the correct adjustment is quite decisive!