I have a Sony 400-disc DVP-CX985V hooked into a Kenwood VR-615 using 6-channel. I was playing an SACD of Bob Dylan's Blonde on Blonde and on the song, "I Want You" I could hear no voice. On another song I could not hear a harmonica. On other songs, it sounded fine. When I connected the components not using 6-channel, I could hear everything fine. What could the problem be?
One setup issue to try would be eliminating all DP on player. I.e. setting all speakers to large, and default volume and distance adjustmens. And to make sure multichannel option is active wherever it appears.
I have ocasionally the same problem on a totally different player. In my case I suspect firmware, which sometimes is updated by manufacturer. Maybe you should check out Sony website.
I will have to take a look at my receiver when it's in front of me to know for sure... There are multiple sound settings on it, and I had the most obvious one set to 6-channel, but under a "sound" button there was another 6-channel that needed to be set. I will take a look at it when I get home and I think I will have a few more questions for you guys about that ;)