Det står ju thru på den ena... Den ska du väl länka till den andra högtalaren... Titta på sidan 15 i manualen. "and paralell outputs" står det...
"Digital inputs and parallel outputs, compliant to S/PDIF standard: These inputs can work with signals according to the S/PDIF standard (optically = TOSLINK and coaxially), which is used by most devices in the consumer electronics field. The digital data stream contains both stereo signals (left and right). By means of the switch “6” the channel which should be reproduced has to be selected"