How to get sound in all (two sets) of Logitech Z623 speakers

[dkali1]

I have attached two sets of Logitech Z623 with PSR s975 Right & Left output. Each Z623 has three speakers (2 speakers and 1 subwoofer). I get sound in both subwoofers and one speaker of each Z623, but don't get the sound in one speaker of each Z623. Is there any way or adapter that I could use and get sound in all six speakers thru s975 audio output?