I just set up my HT system tonight - Denon AVR-1712 with Jamo S606 5.0 speakers (sub on the way).
Ran setup wizard, Audyssey, etc and everything is going fine. Listened to some stereo music on the towers and everything sounds good. Switched over to cable to watch some Olympics and put it in Pro Logic mode to get most sound from the center, with a bit of fill from the L/R. However, in either Dolby mode, only the center and right speaker play... nothing from the left.
Swapped cables completely, and it seems to be working. Though first time I tried swapping through the different sound modes, on the DVD input, in Dolby modes only the center was playing. But now swapping between all modes on both inputs, everything is working.