Originally posted by Pace
Care to tell me more as this just seems stupid, as lower output impedance is always better. Works better with higher impedance speakers too. If HK has this kind of setting, I don't see the purpose...
[EDIT]To me this setting sounds like it might be some sort of treble boost to equal out the roll-off caused by lower impendance speakers.
A digital PWM amplifier uses an inductor filter @ its output to the speaker, these are crucial to match its frequency for the load impedance. Since most loudspeakers are 8 Ohms this inductor is optimized for that load, so that amplifier's frequency response is flat as possibile for the audible bandwidth out to 20kHz..
However if the the speaker impedance is lower
such as 4 Ohms then a filter's designed for 8 Ohms will not be flat out to 20kHz.. There will be a faster rolloff in the high frequencies, making the amplifier's high frequency response to be down by a few dB..
Note the inductor filter can be optimized for any loudspeaker inpedance 4 , 6 or 8 Ohms but only for a single
impedance. Since most loudspeakers are 8 Ohms then this is what the engineer designs to...
Since HK is part of Harman International who own JBL, Infinity and Revel they are fully aware of various loudspeaker impedances so they have designed into the HK digital amplifiers this advanced feature which assures flat frequency response regardless of loudspeaker brand or impedance...