Thank you for reaching out to us for help with this. This is likely due to a technology in HDMI connectivity known as CEC. We can turn that feature off. HERE is a help article on where to find the setting on your PS4 to disable it. Here are the steps for turning it off on your SoundTouch system:
We are thrilled to read about your enthusiasm for the system. It's great that we got this resolved together. Just let us know if you have other questions in the future and we'll be happy to help.