Hi @MLove
Welcome to the Sonos Community!
I too have a Sonos Amp connected to my TV, and what you describe does not happen to me - nor should it - so I can only presume that your TV is sending a signal, via CEC, telling your Amp to set it’s volume to 0. One way to confirm this would be to connect the Amp to a different TV and compare results.
Does this happen every single time you turn the TV off and on again? Or, does it only happen during the night when the TV has been off for a while? It’s possible that the command to turn down the volume is in fact coming from a different source, during the night, but if the problem occurs every time you turn the TV off and on again, then it is most likely the TV.
The sources of volume changes are recorded in the speaker’s logs, so you can find out for sure what the source of the volume command is by getting in touch with our technical support team, who have tools at their disposal that will allow them to give you advice specific to your Sonos system and what it reports.
I hope this helps.