I have finally connected my Xfinity X1 dvr to my Harman Kardon AVR, the video is working but no audio. Here is the detailed description.
1- I connected the X1 dvr directly to the TV HDMI with HDMI cable, video and audio both work fine.
2- I connected the HDMI output of a Sony blue Ray player to the Harmon Kardon AVR 1565 via HDMI cable. Connected the HK receiver HDMI output to the HDMI input of the TV. Both the video and audio worked fine.
3- I connected the X1 dvr to Harmon Kardon AVR 1565 via HDMI cable (X1 HDMI output to HK receiver HDMI-1 input). Connected the HK receiver HDMI output to the first HDMI input of the TV. The video is working but no audio
As described in # 2, the connection from Blue Ray to HK receiver to the TV works fine (both video and audio are ok) and when I turn the volume dial on HK it shows both "-" and "+" Db and audio is fine. But when Xfinity X1 is connected, there is no audio (only video) and the volume dial on HK receiver shows only "-" Db and not the "+" values.