I had tried to listen to Wagner before, Tristan und Isolde, specifically, and I wasn't impressed. But after doing my homework, I discovered a couple of things. One, you really need to get a good recording to appreciate it. I had bought a bargain bin copy of that opera, so I missed the mark there. Two, you need to listen to it at very high volume. Once again, I missed that the first go-around. So I did even more homework, and found the Daniel Barenboim-directed version of the entire cycle and turned the volume way, way up.
In a word, it's sublime.