XG1v4-A

Good afternoon @rraub. Can you provide some more details on what you are requesting? 

@rraub  I've never seen anything like what you describe here or on other AV sites.  Certainly sounds like a Sony TV issue.   It's hard to imagine how a TV set to use its own speakers with HDMI-CEC turned off would switch to external speakers based on a command from the X1 box.  You can try getting a CEC blocker, about $20 on Amazon, which prevents any communication on pin 13, which is how CEC messages are sent. 

@rraub OK.  The CEC blocker prevents CEC messaging by disabling the physical pin.  So, this cannot be a CEC issue.  

How can the audio transmission setting on either device (stereo/PCM or any flavor of Dolby) cause that behavior?

How did you decide the Sony TV detects the X1 as an Audio System and switches from internal to external speakers as a result?  X1 is not an ARC device.  

Thanks for the added info.  Interesting.  Did the Sony people explain how they came to that conclusion? 

It sounds like you are saying the problem happens when the TV and X1 both power up at the same time.  Have you confirmed that (A), if both are powered down, the audio is fine if you turn on the TV with its remote and then wake up the X1 more than :30 later?  Or that (B), audio is fine if the cable box is already running when you power up the TV with its own remote?

As you can probably gather, I am skeptical that powering up the X1 and TV together is causing the speaker problem you are having.   Lots and lots of people have Sony TVs and XG1v4 boxes and I've never seen a post like yours.  I have LGs, Samsungs, and Panasonics paired with various Xfinity boxes and have never had my TVs do what you describe.

@rraub  I did a test on my XG1v4 and LG OLED G2.   Turned everything off last night.  The LG is set to start on the last used input, which was the HDMI from X1.  The XG1v4 was not active with no white light on the front of the box.  I used the LG remote to power up the TV and it displayed an Xfinity splash screen.  Still no light on the front of the box.  Pressed the Exit button on the Xfinity remote which turned on the white light and took me to the channel I was watching last night. 

I don't know what the X1 does when you press the power button on the remote to turn it off.  The white light remains on and, based on this test, it seems like it never turns off, but goes to a sleep mode at some point, outputting a splash screen.  

It appears the X1 boxes never turn off, just go to sleep.  They need to stay on to do recordings and software updates.

Set the Sony TV to Prioritize Pass Through. Set the cable box Audio Settings to Expert Mode. 

Make sure the Sony TV is set to Audio System. 

Make sure your sound system is on the eArc port. 

On the Cable Box - Go to Settings > Device Settings > Power Preferences > HDMI Device Control (HDMI-CEC) > and turn it off. 

Disable Power Savings Mode on the cable box under Power Preferences. 

This should solve your issues.