I have only tried Optrix.It improved the resolution of every CD I have no matter how good or bad they sounded without it.The sound was also more transparent.The result was obvious for every member of my family whether I put the CDs on a boombox or CEC 5100Z player.What's more, I first treated some of my CDs with it over 2 years ago, and there is no deterioration in sound or CDs' surfaces,as far as I can tell.I don't know about you but I have some CDs that are very difficult to find and cost a lot,so the safety of these products is important to me.I will try Walker some day but first on DVDs and wait for a while.