Yeah ,I read it..but it's a little fuzzy to me still..
They are called 'thru/low Out jacks... and it says in the manual...
" This 1/4" jack supplies low-frequency out signals from the activated crossover for patching to additional amplifiers inputs.When the crossover function is not acitvated this jack converts to a THRU function,where the output of the electronically balanced input circuitry is supplied to this jack.
It looks like you can use them either for daisy chaning amps as you would like to do, and the output sends a full range signal for speakers, or you can activate a crossover and send a signal that is intended to be used for subwoofers. Pretty neat IMO.