When connecting a subwoofer to the dedicated Subwoofer Output on either the AXR85, AXR100 or AXR100D, the frequency of the connected speakers is not adjusted and they remain at full range.
This means that adding a subwoofer will not divert the lower frequencies to the Subwoofer Output. Instead, the Subwoofer Output simply duplicates those frequencies (200Hz and below) to your subwoofer.