I had a Level III with Six Bybee filters installed and I can tell you the difference is Night and Day. I could not stand listening to redbook cd's on the Sony before this mod and now with about 50 hrs of listening, it continues to improve with each session. I know, it took some real soul searching for me to shell out the bucks. But after a little bit of burn in, you'll be amazed at how good it sounds. Dan's business is really booming because he delivers.