Apparently, the audio level differences have been addressed when changing from DD/HD channels to SD. This problem was a topic of discussion on retailer chat. Thanks, Tech Guys for saving my wife's sensitive hearing, and possibly my sanity.
I switched back an forth from SD to HD on several channels. Sound level was consistent. Commercials are always louder!!
Goes to show you. When the tech guys sucessfully solve an issue, no one notices. Looks like we would rather complain about what is yet to be corrected, than thank them for their efforts, when an issue is addressed. Interesting!
I hardly watch SD anymore with my HD only package so I hadn't noticed, but I remember it being quite an annoyance having to turn the volume down every time ...