Only NBC HD and CBS HD channels 804 & 802 have sudden very low volume. All other channels ok. Restarted the box. Changed audio between expert mode and Dolby 5.1 ( best available) but no change. Audio is connected to my sound bar by HDMI. All was working fine for the 2 weeks I had the box till the Jesus Christ Superstar show last night where I had to turn the volume to max and still did not have a great experience.
Comcast please check.