I remember something like this effect on records when I was a kid (in the 70s), on inexpensive systems, although I think the faint sound happened slightly before the real sound. I don't know what caused it, and I can't remember hearing it on any CDs. I don't know if the effect I heard is from the same cause as your experience. Perhaps the CDs were mastered from records? Or perhaps it is a result of analog reverb machines? I wish I knew, but it brings back memories.