But, in my experience, the way that's implemented is that when there's an announcement, everyone's volume is temporarily overridden to 100%.
Hence my solution: Set things up so your volume is always at 100%, and the inline volume control device is throttling that down to a comfortable level.
Mine too. I believe you're exactly right here. Volume seems to be attenuated from 100% at the armrest by the digital control, and overridden back to 100% when the PA is keyed. I've done exactly what you described and I stopped getting audibly assaulted on flights where I opted to listen to channel 9, or to watch a censored movie.
