So, full frequencies thru the speaker outs, but only 100Hz and lower thru the sub out?
I believe that is the case. I think it's sending full range through the speaker jacks all the time, while simultaneously sending a low-passed signal through the sub out. So, you'll never have the 10 Hz "gap" in the signal sent to your speakers.
Also, if/when you get it, make sure to read the manual about the loudness control. Used properly it's amazing...I wish more modern high end amps would have it.