Active 2.1: By connecting a single ALF40 to its own amplifier channel, its
output relative to the AIW1X/AIW3X pair can be set optimally. In larger
rooms care should be taken not to adjust the relative output of the ALF40
so high that its mechanical limits are reached well before those of the
accompanying AIWX speakers – consider using two ALF40s if this is the
case [see Active 2.2].