I found a similar but 4 year old thread about this so I am asking here. I have had a 622 for 5 years using the toslink out to my Marantz AV receiver which is in Auto mode. It detects whether the signal is stereo or Dolby Digital automatically. I just had the 622 replaced with a 722K for another (video) issue. Now, using the same toslink cable, the 722K has a huge volume difference between the SD channels in stereo and the HD channels in Dolby Digital. The mode indicator on the Marantz AV receiver continues to indicate the proper signal it is getting- stereo or Dolby Digital. It also shows the audio channels it is receiving- L R or L R C LR RR. When I change from HD to SD the volume decrease seems like it is completely gone but if I crank the volume to max, it is there. If I unplug/replug the toslink on either end while on an SD, the volume comes back. Change to an HD and then back to SD and I lose the volume again. I changed to another toslink input on the AV receiver and the issue is still there. I bought another, cheap $10, toslink cable and the issue is still there. I have unplugged the 722K from power to reboot also. While at a lower volume on an SD channel, if I power down (w/remote) the 722K and power it back up the issue remains. If I instead power down the AV receiver and power it back on, the issue resolves until I change channels again. A Dish service person says it has to be the cable and that I should get a better one. The 722K has already been changed out for this issue. I have changed to No Audio Levelling and Line audio settings on the 722K. My AV receiver does not have HDMI so that is not an option. This makes TV watching unbearable unless you stay with either HD only or SD only. I am hopeful someone has some ideas or can point out something I have missed. OK, just bought and installed a $30 Monster Cable THX toslink cable- same issue! And some more info: the 622 was replaced last week when trying to resolve the video issue. The toslink worked fine through that switch out so it seems like this is a 722K issue. Perhaps a compatibility issue with the Marantz AV receiver?