Ignorance vs. Interest

What's the relationship between Ignorance and Interest? Is it possible to be interested in something you know everything about? Is it possible to know a subject so completely that it is not possible to know anything more about it? Or can new things always be discovered about any subject? What is more interesting: the things you know about a subject or things you don't know very much about? It seems to me that the things I don't know much about are more interesting, since the stuff I already thoroughly know is now just practical knowledge, or perhaps it's even forgotten.

When I pursue music, for example, what I'm most interested in are those records I've haven't heard enough times to completely understand or get everything out of. In other words, records that I am still somewhat ignorant of. Even when it comes to one album, once I've listened to it enough to have absorbed it completely, memorized it, it loses interest. Conversely, the albums that I can't quiet get my head around are the ones that hold the most interest for me and I will likely be listening to for a long time to come.

I think the same thing applies generally. I believe that a certain amount of ignorance is required to create interest. As if there is a buffer zone between a body of knowledge and the realm of ignorance around it that pulls you from one to the other. I think it is also possible to nurture and care for that buffer, by continually pursuing related items, i.e. those items that we are neither completely knowledgable of nor completely ignorant of, so that our interest is always maintained.